Haven't watched the video however this is what happened:
About 1 year before 911 a contractor was hired to "replace the fire retardant" on the structural steel throughout the whole building.
This is documented truth and can be found easily in web searches.
The contractor then applied a thermite rich paint to the surface of the steel, and strategic small incendiary devices after which a spray foam fire retardant was used to cover it all up.
The Contractor had access to the entire building.
The thermite was triggered by the "plane" (rocket, whatever) and the devices were triggered causing the structure to collapse.

Not to mention that Silverstein, the buildings owner, took out terrorist insurance on the building about the same time.
Coincidence?
No.