This is the text that displays when you open up the beta.
In short, we've asked people not to post any images or videos up. The reason for this is simply there are glitches and balance issues, and we don't want people to see the game in a sub-optimal state when we're this close.
Our fan base is cool enough to adhere to this which is, I think, why nothing has been posted. It's not legally binding but it would be pretty disappointing if people did post things. But they haven't, because we have awesome fans.