Wow and I mean WOW!  Please follow up with this guy after showing him the video and do another interview.  He might open up.  His impediment seems to be he is unable to wrap his mind around how they cold have snuck the explosives into the building undetected and the planning involved.  How does a steel framed building come down at the rate of freefall in the direction of maximum resistance?  ie:  80,000 TONS (160 Million pounds) of steel and concrete are in the way.