I have revisited and extended some of my early measurements of high speed massive projectiles from the World Trade Center on 9/11. The results for the three projectiles measured: 55 mi/hr, 45 mi/hr, and 78 mi/hr. I don't claim this is smoking-gun evidence of explosive demolition all by itself, but it is part of the puzzle and it is more compatible with the explosive demolition hypothesis than simple gravitational collapse.
(On a technical note, if you are looking at the numbers in the three measurements, the third measurement is taken while the video was zoomed in, relative to the calibration frame. The numbers shown have to be scaled down by a factor of 1.701 to give the stated results.)