This video just pushes old, long answered canards.
First of all, molten metal could indeed have formed in the rubble piles post collapse. KBR SH&E recorded underground temperature ranges "to more than 2,800F" (Professional Safety, May 2002, "SH&E at Ground Zero). So that's no surprise. It doesn't butress the theories of thermite one whit, since the metal could have easily melted post collapse, and the thermite/thermate theories still suffer from all the arguments against them, not to mention the lack of any characteristic signatures on the debris that was recovered and studied. The burden of proof still rests on the fantasists to prove that thermite/thermate was used in the towers collapse, and this video isn't it.
Also, note how Steven Jones jumps from "molten metal" to "molten steel". Steel wasn't the only metal present in the towers. That's a handwave right there. The entire facade, if I remember correctly, was aluminum (others can either correct or go into more depth for me).
On top of that: Thermite burns out in seconds. By admission, the pools were witnessed weeks after the collapse. What kept them molten? The hot fires mentioned above. Why couldn't they have been molten prior to settling in the debris piles? I don't know, but the burden of proof about that rests on the truthers, and they're trying the reverse here: Use these sightings as proof steel melting caused the collapse. These sightings do not support that.
And: Thermate? Where's the barium signature then? This cherry picking of characteristics was debunked a long time ago. The sulfur noted could have come from various, more probable sources: Drywall, acid rain, computer monitors, diesel emissions...
There's really nothing new here. Just search this forum for "molten metal" and "molten steel", thermite, thermate, sulfur, etc., to see the arguments. And note the dates; I'm not kidding when I say this is old fantasy.