I was just reading this interview and I found this part. It sounds really great and I can't wait for it to be implemented into the game. It sounds perfect:
Awesome. So we'll be able to save all our coolest moments without having to have a demo recording 24/7 . And the demo won't break every time Valve release a TF2 update. Can't wait for that. There might be more exciting info later on in the interview I don't know, i've only got that far. The interview questions were sent just before the Spy v Sniper update so a few of the questions and answers are outdated.TFPortal.de: In an E-Mail you mentioned a new demo type / format which you are developing. Many players have broken demo files after downloading new updates. Can you tell us a bit about it?
It's getting close to being releasable in a beta form. The idea is that after you die or finish a round, and it was a round you were particularly happy with (maybe you scored an awesome kill, or saved the entire team with an ubercharge), you can ask the server to send you a demo of it. The server then sends you a demo that it recorded, which has the complete game state instead of just what your client saw, and it's in a format that's robust and won't break as easily when we update the game. In addition, the format has a some side benefits, like supporting full backwards & forwards time scrubbing.