The terrorists figured it out. Cause panic and confusion and they won't know where to deploy their military until it's too late. Plans go out the window when you can't figure out what is going on. Though as the video pointed out, they should have known something when the plane was coming in too low, but even at that point it was really too late. Still after the first hit, they should have grounded all the planes. All of this is 20/20 hindsight though, but with so many conspiracy theories floating around about this one incident, this video doesn't really help the governments case.
What i DON'T believe is that aircraft hits caused collapse of twin towers.
It can't be the physical impact, neither it can be the fire ball of jet fuel.
Going by rules of science and physics, aircraft should have shattered away upon impact, instead of slicing through the thickest concrete+steel columns.
Engineers across the globe have same view.
Besides this, their are forensic indicators, which suggest it's something else. Like the melted steel and concrete residue, which require thousands of degrees of temperature to take place.
Collapse of 3 tower etc.