The Purdue film

Of course, as you can see from the comments, it won't persuade the "truthers". Right now the top commenter insists steel buildings don't collapse, and then his post descends into misspelled gibberish
...ummm..an engineer would point out the stress bearing load of each steel column and how an increase of temperature and the increased load due to destruction of x number of load bearing columns and then say when it will collapse. That I might listen to, but not gibberish.

Then we have the guy who says there is no paper evidence of Alqaeda being behind the plan, which might be news to the Philippine police who discovered early versions of the plot after a local Alqaeda operative's apartment had a fire...bombing of airplanes and flying into buildings were already being proposed in the mid 1990's. Probably when the bomb didn't take down PAL flight 434, they decided they'd better fly them themselves.