I'm not so sure about the concrete -- it appears to have separated very easily from the rebar, with only a few attached pieces. That should not happen absent some kind of force that would destroy the concrete other than a simple gravitationally induced collapse. And there is no evidence of any such other external force.
Seeing the video, the problem seems to start at the top. I know that’s where the distortion would first be visible, but there’s no indication of anything amiss in the lower floors. It just pancakes from the very top. I’m super curious. As for the rebar separating, well could be the columns, but the floors seem to be hanging on really well as a curtain effect. I’m assuming it’s the tension cables holding it together.
It looks to me like the upper floors are steel construction with steel columns, beams and Robinson or Verco deck (corrugated steel) with concrete poured on top. The lower floors appear to be cast concrete with post tension decks.