TF2 Pyroworld / Pyrovision textures..?

Theory has it that it's an embedded shader. Which makes sense as presumably the maps havn't been re-compiled. To actually find the texture would require you to extract it. But this is speculation on my part as i havn't actually looked into it myself. Just passing on the gossip.

If you want to find it, extract it from the regular texture area in the TF2 materials GCF, using Nem's GCFScape.

It is indeed most likely an embedded shader, but their are vtfs that it uses to choose colors. You can find them all in materials/rj