From the looks of things, it appears as if one sneaky entrant in the Gamescom DOTA 2 tournament has been recording their screen! Here's a quick video that shows quite a lot of doing nothing at a menu, but then from 1:28 onwards, it's all in game action. The environment looks nice and lush, and the characters are quite bright and colourful. Definitely cut a line that plunges right into the middle of the MOBA-maelstrom of LoL, HoN and others. Also the commentators sound VERY EXCITED. Check out the footage below:
Did you sign up for the beta yet? (Actually that might be down, now. Hmm.)
Alternative livestream of the thing here. Thanks, Tei!