https://m.youtube.com/watch?v=m6-2-hXiL4Q @3:17 there are shots from atop a nearby 30 story building looking into part of the pavilion. Mind there were 6 basement floors all with high ceilings, the towers collapsed into their foundations pretty much as well as could be expected and that means there two huge voids packed with rubble you can't see. The dust isn't just from fire it's also powdered concrete from the floors, each floor was about 4 inches of concrete resting on steel trusses meaning aside from the central elevator shafts there were no columns just the outer steel frame holding it up making it a radically airy space the rubble would be less than you would expect from conventional construction. https://www.newworldencyclopedia.org/entry/World_Trade_Center#Core there is a map of the wtc compound in this link that might help you orient the footage from the video.