So it was with God of War III, so it is with Uncharted 2. If something is going to be shown behind "closed doors" at GDC, there's a good chance somebody will film it regardless.
The footage seems to have been shot by some Italian kids. As you can see, there's shooting. There's rolling. There's climbing. Just like the first one, only in a new place. Which really, is all we're asking for!