[lch]

I am not an expert, but molten steel doesn't convince me. During the disasters in the Alps tunnels and similar disasters like that where things worked like a chimney there were extreme temperatures, too. It might have come from one of the elevator shafts. I didn't see this WTC7 collapse thing before, but that one the other hand is really a troublesome video. It looks exactly like a controlled implosion, and AFAIK those really aren't easy to do, you need experts so that it doesn't collapse to one of the sides.