Hate to say it

For those curious about how much of this is in game, here are some excerpts of emails from Valve's Robin Walker

Robin: Actually, everything in that trailer is in-game. There's some extra screenspace effects on it (depth of field & motion blur), but apart from that it's all just recorded in the game. So yep, that's what the models look like, and that's what 2fort looks like now.

When asked specifically about which animations are indeed from gameplay, here is Robin's reply. It seems that everything except the Spy animation is indeed actual gameplay footage.

Robin: Almost all of the animations are game anims used while playing (scout run, hwguy firing, etc). The exception is the Spy. We don't have a disguise effect we're happy with yet, so we whipped up that animation to give new players an understanding of what the Spy class is about.

We still haven't decided how we'll use screenspace effects. It's more of a design issue than anything else.