David Ray Griffin says:

Almost Free-Fall Speed: Buildings brought down by controlled demolition collapse at almost free-fall speed. This can occur because the supports for the lower floors are destroyed, so that when the upper floors come down, they encounter no resistance. The fact that the collapses of the towers mimicked this feature of controlled demolition was mentioned indirectly by The 9/11 Commission Report, which said that the "South Tower collapsed in 10 seconds" (Kean and Hamilton, 2004, p. 305).[22] The authors of the report evidently thought that the rapidity of this collapse did not conflict with the official theory, known as the "pancake" theory. According to this theory, the floors above the floors that were weakened by the impact of the airliner fell on the floor below, which started a chain reaction, so that the floors "pancaked" all the way down.

But if that is what happened, the lower floors, with all their steel and concrete, would have provided resistance. The upper floors could not have fallen through them at the same speed as they would fall through air. However, the videos of the collapses show that the rubble falling inside the building's profile falls at the same speed as the rubble outside[23] (Jones, 2006). As Dave Heller, a builder with degrees in physics and architecture, explains:

the floors could not have been pancaking. The buildings fell too quickly. The floors must all have been falling simultaneously to reach the ground in such a short amount of time. But how?. . . In [the method known as controlled demolition], each floor of a building is destroyed at just the moment the floor above is about to strike it. Thus, the floors fall simultaneously, and in virtual freefall. (Garlic and Glass 6)

Total Collapse: The official theory is even more decisively ruled out by the fact that the collapses were total: These 110-story buildings collapsed into piles of rubble only a few stories high. How was that possible? The core of each tower contained 47 massive steel box columns.[24] According to the pancake theory, the horizontal steel supports broke free from the vertical columns. But if that is what had happened, the 47 core columns would have still been standing. The 9/11 Commission came up with a bold solution to this problem. It simply denied the existence of the 47 core columns, saying: "The interior core of the buildings was a hollow steel shaft, in which elevators and stairwells were grouped" (Kean and Hamilton, 2004, 541 note 1). Voila! With no 47 core columns, the main problem is removed.

The NIST Report handled this most difficult problem by claiming that when the floors collapsed, they pulled on the columns, causing the perimeter columns to become unstable. This instability then increased the gravity load on the core columns, which had been weakened by tremendously hot fires in the core, which, NIST claims, reached 1832°F, and this combination of factors somehow produced "global collapse" (NIST, 2005, pp. 28, 143).

This theory faces two problems. First, NIST's claim about tremendously hot fires in the core is completely unsupported by evidence. As we saw earlier, its own studies found no evidence that any of the core columns had reached temperatures of even 482°F (250˚C), so its theory involves a purely speculative addition of over 1350°F.[25] Second, even if this sequence of events had occurred, NIST provides no explanation as to why it would have produced global—-that is, total--collapse. The NIST Report asserts that "column failure" occurred in the core as well as the perimeter columns. But this remains a bare assertion. There is no plausible explanation of why the columns would have broken or even buckled, so as to produce global collapse at virtually free-fall speed, even if they had reached such temperatures.[26]

http://911review.com/articles/griffin/nyc1.html

The "free fall" issue is addressed on the debunking sites that Olesko and the others parrot, and that's why I like Griffin's work. His last book debunked the debunkers. He tore up the Popular Mechanics junk science piece and 3 other "deunking" reports.