Cognitive-Dissonance impaired opponents of the Video-Fakery analysis of 9/11 invariably get hung up on a question such as this:
"Why in the world would anyone fake videos that show the official account of their collapse cannot be correct?"
Here's my answer:
A really effective psy-op needs a strong and long lasting EMOTIONAL PUNCH!!!
Network
 television's endlessly repeated, astonishing, CGI-fabricated videos of 
the top-down, descending-and-dissolving "Tower Volcanoes" (great term!) 
were intended to be far more spectacular, shocking and gut-wrenchingly 
memorable than would have been some genuinely live, close shots of the 
way each tower actually fell, mostly cloaked behind a massive 
smokescreen -- as the result of an actual, bottom-upwards, controlled 
demolition. (And how could the public, even as gullible as they proved 
to be, ever accept a bottom-up collapse being caused by a fire at the 
top?)
The decision to eventually assign NIST to "explain" the 
towers" collapse may or may not have been part of the original plan -- 
but hey, no matter! 
What those much-credentialled, "scientific' 
experts were then confronted with was their "patriotic duty" to come up 
with a highly technical-sounding EXCUSE for the towers' inability to 
survive the very kind of damage they were purportedly designed to 
withstand. 
And since attributing the buildings' collapses to 
violent, internal forces generated by ANY kind of pre-planted explosive 
devices would have been an IMPERMISSIBLE, even UNTHINKABLE HERESY, those
 NIST boffins were "boxed in" to a seemingly inescapable quandry.
So,
 after "dragging their feet" through a long series of delays, they 
finally decided to ignore BOTH the spectacularly false videos AND the 
institute's mandate to use them as "evidence" in explaining the 
destruction. Instead, those cowards-in-white-coats "punted," releasing a
 convoluted, tortuous and lengthy critique of the towers' alleged 
construction-design flaws -- a "study" that ends its timeline just as 
each collapse is about to begin its television-depicted, IMPOSSIBLE, 
free-fall descent.
And since the controlled media would, of 
course, brook NO serious questioning of NIST's suspicious avoidance of 
explaining the (occultically symbolic) 9- and 11-second "volcanic" 
freefalls, the perps could sleep well, knowing they got away with it.