Here's what I was half-expecting in Meet the Pyro:
Pyro unceremoniously unmasks and reveals identity near beginning of video.
Back-and-forth cuts (like in the older MtT vids) between unmasked Pyro casually explaining its backstory, removing all mystery, and masked Pyro on battlefield doing awesome stuff. In a shocking twist, unmasked Pyro suddenly reveals itself to be a disguised Spy. Just as the now undisguised Spy is about to tell the viewer what the Pyro's actual identity is, the masked Pyro jumps in and kills him.
I'm not quite sure whether I'm disappointed or happy. Both that concept and the real one lack the personality and subtlety of the other MtT videos, but I think that's mostly the fault of the Pyro class. You can't really play with the nuances of a character when the character is defined by its lack of definition.