Ketcham; I don’t even have to follow the link. By his own admission he’s just a software designer who got taken in by 9/11 Trutherism several years after the events. He has no experience in mechanical engineering, he never worked on the NCSTAR reports, never even worked in that department of NIST nor any related to it. He just repeats all the superficially-convincing-but-utterly-wrong stuff you’ll find at the A&E9/11″Truth” site; he doesn’t even add a single original idea.
The video’s worth watching though for the clips of the collapse of WTC1; it has the best clips of the core remnants I’ve found anywhere. Very ironic in that Ketcham keeps asking how the building could have fallen unless the core had been dynamited, yet you can see it still standing briefly after the internal collapse had smashed all the floor assemblies out and the perimeter had peeled outwards.
These people used their eyes and brains, and got it more right than anyone else: