I haven't watched more than a few minutes yet, but here's the first 15 minutes of portal 2. It sounds like, full walkthroughs of the single player and multiplayer will be posted within the next day or two.
I don't want to spoil exactly what makes this level of Bulletstorm so much fun, but it starts off with a miniature cityscape, and then around six minutes in makes clever use of a cyborg Godzilla.
Here's part one of a Bulletstorm playthrough (profane language). (It's too bad they couldn't go all the way and give him white skin and a hook like Lobo.)
Full playthrough of the scary and gory Dead Space 2 demo. It's starts off with a summary of the events of Dead Space 1. (I definitely prefer the suit from the first game to the new version.)
Here are the first two parts of a full playthrough of the Tron Evolution game. The videos do a good job of capturing everything that's wrong, and right with the movie - - the action is exciting and stylish, but the dialog is unbearable. At least this explains the totally extraneous genocide talk in the movie - - it's apparently what the game is all about.
I wish the cityscape with Recognizers menu screen was available as a screensaver.