A frequent cornerstone of the 9/11 Truther arguments is that WTC 1,2, and the largely unregarded 7 fell because of demolitions. Questions about when the several tons of explosives which would be required were planted are usually shrugged off. As evidence, they point to videos which "clearly" show the towers moving at freefall speed. No, demolitions usually aren't at freefall, but they think they are.
Here's a video to the contrary;

It uses audio analysis to estimate when the buildings fell, and points out that it took much longer than freefall would've taken.
Here are the comments. I'm EGRJ. At a certain point in them, you'll notice someone called SexyMelon. SM declared RKOwens, the guy who made the video, to be "totally incompetent".
I pounced.
The following is a paraphrase, based on my imperfect memory. I'd go back into the comments themselves, but then I'd be tempted to wade back in.
J: So you can prove that both his premises are wrong, right?
SM: What are you talking about?
J: You called him "totally incompetent". That means his premises are wrong, his reasoning is wrong, and his conclusion is wrong.
SM: What?
J: One premise is that it would take 9.22 seconds for the top of the towers to take the ground. The other premise is that the towers took about 14 secs and 20 secs. The reasoning is that both of those numbers are larger than it should've taken under freefall. If he was "totally incompetent", both premises and the subsequent reasoning would be incorrect.
I believe she said something about how the "dislikes" were winning, and then;
J: You're making a point about the average intelligence of people.
...On Youtube.
SM: Youtube is the most popular site on the Internet. This is the WORLD's opinion.
J: Even the 25% of it without power, much less access to YouTube? There's a difference of 7% in the Truthers' favor. Hardly a landslide.
She (I assume) asserted that the video was unprofessional and unsourced, and derided the fact that RKO expected the people to believe some random video on Youtube. I pointed out that she had just said YouTube was the world's opinion.
Over time, the discussion wended its way to the NIST report. Unlike most Truthers, SM was perfectly willing to use the portion of the NIST and 9/11 commission reports on the matter giving the length of time it took for the towers to fall. (~10 secs) Oddly enough, she later claimed it was impossible to measure how long it would've taken.
I accused her of cherry-picking the potions of the gov't reports that supported her argument, like most Truthers. she said that it was just "common ground".
There's a lot more, but I cut it out.
J: Say, if you're using gov't sources and other Truther's are not, how are you coming to basically the same conclusion?
SM: I don't know what you're trying to talk about.
J: If other Truthers aren't using gov't sources, and you are, yet you are arriving at the same conclusion, then either gov't sources redundant and aren't necessary to reach the "correct" conclusion, or the other Truthers are using bad logic yet accidentally arriving at the right conclusion.
SM: nope.avi
Cue a lot of screeding about lumping groups of Truthers together, how I was confusing reasoning and conclusions, etc.
J: Brass tacks; are gov't sources needed or not?
SM: We need to get back to the matter at hand, and quit branching off on these red herrings. Address the evidence. I suspect you're trolling.
J: Sure, good buddy! Wait, there was one thing that was never answered. For the tenth time, can you prove RKO's first premise was incorrect, and that he was "totally incompetent"? I mean, it's not like it's relevant anyway, since we've established that one can't tell how long it took for the whole thing to fall. All it takes is for you to admit you were wrong.
SM: Quit it with the amateur psychoanalysis. I already told you, you can't measure how long it takes for the WTC to fall accurately.
J: That's not what I'm asking. I'm asking if you can prove RKO's first premise wrong.
SM: You can't measure how long it takes for the WTC to fall accurately.
J: I'll even link to a website with the reasoning. He got the height of WTC 1 and 2 right, and the rate of acceleration is correct, so that leaves his fairly simple reasoning. Please refute it the two fairly simple equations he used.
SM: You can't measure how long it takes for the WTC to fall accurately.
J: That just means that his claim of how long it took isn't verifiable. That's the second premise. Was the "total incompetent"'s first premise wrong?
SM: You can't measure how long it takes for the WTC to fall accurately.
J: This does beg the question of how you can determine the building was in "free fall" without knowing how long it took to fall. Distance, time, and velocity. We have distance, you claim time is unknowable, so velocity is impossible to work out. However, all that is irrelevant to the question of whether his primary premise was incorrect.
I would like to point out, gentle reader, that I'm an art major. Animation, technically, yet with my--wow!--ten-year old high school physics knowledge that I've mostly forgot, I was still able to argue rings around her.
Sometimes it's nice to be clever.
SM: Are you taking the piss? I already proved it was wrong!
J: No, you didn't. In fact, you avoided doing so repeatedly.
Good day.
The amazing thing is that she's not even aware she's contradicting herself. She'll say you can't tell how long it took for the whole thing to fall, yet insist it fell at freefall acceleration. She is refering to the NIST report, which said that WTC 7--and part of it, at that--fell at free-fall speeds. This was after the NIST's draft of the report was modified to clarify that 7 fell at slower than freefall, then the North Face at freefall for a few seconds, then slower than freefall. I know the difference in between what she meant and what she said, yet she'd still never admit to something as simple as a misphrase, even if I offered her a no-fault way of doing so.
Well, it was fun while it lasted. I haven't even mentioned the crazy guy whose favorite words seemed to be "swallowing" and "coward". You really don't want me to elaborate.
EDIT: Allow me to summarize another conversation elsewhere;
Suz: Why does the gov't resist an independent investigation that throngs of the public are crying out for?
J: Leaving aside the facts that your "throngs" are a thousand-odd engineers who make up roughly 0.1% of the US population thereof, much less the world's, what's the point of an investigation if Truthers have been able to "determine" exactly what happened just by looking at stuff on the Internet?
Suz: We can't actually know what happened without an investigation.
J: Thank you.
Yeah, it's been a boring few days.
Here's a video to the contrary;

It uses audio analysis to estimate when the buildings fell, and points out that it took much longer than freefall would've taken.
Here are the comments. I'm EGRJ. At a certain point in them, you'll notice someone called SexyMelon. SM declared RKOwens, the guy who made the video, to be "totally incompetent".
I pounced.
The following is a paraphrase, based on my imperfect memory. I'd go back into the comments themselves, but then I'd be tempted to wade back in.
J: So you can prove that both his premises are wrong, right?
SM: What are you talking about?
J: You called him "totally incompetent". That means his premises are wrong, his reasoning is wrong, and his conclusion is wrong.
SM: What?
J: One premise is that it would take 9.22 seconds for the top of the towers to take the ground. The other premise is that the towers took about 14 secs and 20 secs. The reasoning is that both of those numbers are larger than it should've taken under freefall. If he was "totally incompetent", both premises and the subsequent reasoning would be incorrect.
I believe she said something about how the "dislikes" were winning, and then;
J: You're making a point about the average intelligence of people.
...On Youtube.
SM: Youtube is the most popular site on the Internet. This is the WORLD's opinion.
J: Even the 25% of it without power, much less access to YouTube? There's a difference of 7% in the Truthers' favor. Hardly a landslide.
She (I assume) asserted that the video was unprofessional and unsourced, and derided the fact that RKO expected the people to believe some random video on Youtube. I pointed out that she had just said YouTube was the world's opinion.
Over time, the discussion wended its way to the NIST report. Unlike most Truthers, SM was perfectly willing to use the portion of the NIST and 9/11 commission reports on the matter giving the length of time it took for the towers to fall. (~10 secs) Oddly enough, she later claimed it was impossible to measure how long it would've taken.
I accused her of cherry-picking the potions of the gov't reports that supported her argument, like most Truthers. she said that it was just "common ground".
There's a lot more, but I cut it out.
J: Say, if you're using gov't sources and other Truther's are not, how are you coming to basically the same conclusion?
SM: I don't know what you're trying to talk about.
J: If other Truthers aren't using gov't sources, and you are, yet you are arriving at the same conclusion, then either gov't sources redundant and aren't necessary to reach the "correct" conclusion, or the other Truthers are using bad logic yet accidentally arriving at the right conclusion.
SM: nope.avi
Cue a lot of screeding about lumping groups of Truthers together, how I was confusing reasoning and conclusions, etc.
J: Brass tacks; are gov't sources needed or not?
SM: We need to get back to the matter at hand, and quit branching off on these red herrings. Address the evidence. I suspect you're trolling.
J: Sure, good buddy! Wait, there was one thing that was never answered. For the tenth time, can you prove RKO's first premise was incorrect, and that he was "totally incompetent"? I mean, it's not like it's relevant anyway, since we've established that one can't tell how long it took for the whole thing to fall. All it takes is for you to admit you were wrong.
SM: Quit it with the amateur psychoanalysis. I already told you, you can't measure how long it takes for the WTC to fall accurately.
J: That's not what I'm asking. I'm asking if you can prove RKO's first premise wrong.
SM: You can't measure how long it takes for the WTC to fall accurately.
J: I'll even link to a website with the reasoning. He got the height of WTC 1 and 2 right, and the rate of acceleration is correct, so that leaves his fairly simple reasoning. Please refute it the two fairly simple equations he used.
SM: You can't measure how long it takes for the WTC to fall accurately.
J: That just means that his claim of how long it took isn't verifiable. That's the second premise. Was the "total incompetent"'s first premise wrong?
SM: You can't measure how long it takes for the WTC to fall accurately.
J: This does beg the question of how you can determine the building was in "free fall" without knowing how long it took to fall. Distance, time, and velocity. We have distance, you claim time is unknowable, so velocity is impossible to work out. However, all that is irrelevant to the question of whether his primary premise was incorrect.
I would like to point out, gentle reader, that I'm an art major. Animation, technically, yet with my--wow!--ten-year old high school physics knowledge that I've mostly forgot, I was still able to argue rings around her.
Sometimes it's nice to be clever.
SM: Are you taking the piss? I already proved it was wrong!
J: No, you didn't. In fact, you avoided doing so repeatedly.
Good day.
The amazing thing is that she's not even aware she's contradicting herself. She'll say you can't tell how long it took for the whole thing to fall, yet insist it fell at freefall acceleration. She is refering to the NIST report, which said that WTC 7--and part of it, at that--fell at free-fall speeds. This was after the NIST's draft of the report was modified to clarify that 7 fell at slower than freefall, then the North Face at freefall for a few seconds, then slower than freefall. I know the difference in between what she meant and what she said, yet she'd still never admit to something as simple as a misphrase, even if I offered her a no-fault way of doing so.
Well, it was fun while it lasted. I haven't even mentioned the crazy guy whose favorite words seemed to be "swallowing" and "coward". You really don't want me to elaborate.
EDIT: Allow me to summarize another conversation elsewhere;
Suz: Why does the gov't resist an independent investigation that throngs of the public are crying out for?
J: Leaving aside the facts that your "throngs" are a thousand-odd engineers who make up roughly 0.1% of the US population thereof, much less the world's, what's the point of an investigation if Truthers have been able to "determine" exactly what happened just by looking at stuff on the Internet?
Suz: We can't actually know what happened without an investigation.
J: Thank you.
Yeah, it's been a boring few days.