The National Geographic hit piece on 9/11 truth aired 2 nights ago. It was called "9/11 Science and Conspiracy" or something similar. I recorded it and will get around to a more rigorous critique at some point.
A few observations of the top of my head -
1. The editing was malicious in the extreme. The "truthers" - Dylan Avery, David Ray Griffin, and Richard Gage, were barely allowed to say anything. Though I have differences of opinion with Gage on explosive type used, Gage can do a competent job of explaining the evidence for explosive demolition. In particular, I have heard Richard gage point out that the steel floor pans were disintegrated. I am very confident that Richard Gage must have offered a good deal more substantive material than Nat Geo chose to include.
2. The softening beam experiment. Nat Geo built a nice kerosene fire under a loaded steel beam, and got it to sag and fail quite quickly. OK. So what? How could a fire in the twin towers get ALL of the beams in a story to fail at the same time?
Worse, assume all of the support in a story fails at the same time. Assume it melts. Assume it evaporates and disappears, allowing the upper structure to fall unimpeded down onto the lower structure. How does softened support at floor 96 explain how the entire tower exploded into dust? How does it explain the mushroom cloud? How does it explain the dust tsunami? How does it explain the particle size?
3. The projectile experiment. They shot an aluminum cylinder at some walls, and it penetrated, leaving holes roughly in the shape of the projectile. FIrst of all, the holes weren't circular, they were ripped out.
But more importantly, what happened to the projectile? Nat Geo didn't show us. The projectile emerges out the back side after passing through several walls. I suspect the projectile sustained little damage. This makes sense. It was stronger than the walls, so it made a cutout of itself, and went through. On 9/11, we're asked to believe that airplanes made cutouts of themselves, but then disintegrated. It makes no sense.
4. No det cord means no demolition. Nat Geo tried to suggest that because the rubble had no det cord, and it would have taken workers months to rig a standard demolition, and would have needed to cut away walls, it couldn't have been demolished. This simply means it wasn't a standard demolition, which is quite obvious anyway.
5. David Ray Griffin said the twin towers "imploded" and went "into their footprint". This is false, disinformation from David Ray Griffin. The towers EX-ploded, not IM-ploded. The mass of the towers went almost entirely OUTSIDE the footprint, which is one of the best proofs of explosive demolition. Official collapse modelers Frank Greening and Zdenek Bazant agree that anything more than 20% outside the footprint rules out a gravity collapse.