When I first saw the video, I said it looked like a planned implosion. I do not think it was that, but it certainly looked like it. My doubt is based on an implosion requires a series of small charges in specific locations and I did not think they could be planted in an occupied apartment building without someone noticing. But it certainly did fail straight down on itself.
Either this will feed more conspiracy theories or put to bed some that claim the Twin Towers was an inside job because it couldn't happen that way otherwise.