There are some high powered intellects on the board you linked ;)
"Footage shows explosives were placed in both towers before the attack to cause the towers to disintegrate into dust....
The top of the south tower began to collapse sideways, then righted itself, falling into it's footprint. This is impossible with only gravity working to collapse the tower."
Of course what really happened was that the top portion did collapse more on one side than the other, but then that part fell more or less straight down, canted over, as the floors below it pancaked. The upper floors, in both towers, were not destroyed during the collapse, but rather when they reached bottom.