The stuff on the energy of the falling building creating enough heat to have steel chunks glowing hot weeks later is bizarre.
Certainly materials that were already on fire dropping into a big pit and the fire being fed by more flammables already down there could make it a big barbeque, that is logical.
The flowing metal out the 78th floor window would require pressurized oxygen or something similar before a jet fuel fire could be intense enough to melt it to a flowing condition. A simple fuel fire alone will not do that.
I work with melting aluminum and steel every day. I don't have a Spin Doctorate degree in it but throw the textbooks in that aluminum fire and observe it in actual practice.