My take:
E-Team set the cookie-cutter explosives.
The B-Thing is the calibration point for the downward sat beam intersecting with the horizontal beam.
On the day the two beams intersect at full power, moving down the building, turning it to dust. Two passes.
They like leaving clues.
All WTC buildings were destroyed.
Some knew how.
Weapons test.
Power projection.
Warning.
The psychopaths really overdid the Holowwood factor for our benefit.
You know the rest.