This is such a great piece of technology, here are some of the finer points I enjoyed:
You can watch anyone playing on the game without lag or interference.
Cross network chat. Voice chat with anyone, anytime, anywhere.
-think about this: You're friend says, how do you get the item in such and such level? You load up the game, and he watches. You go over to where the item is and say, this one? And he says "no, the one behind you". You then perform the necessary action to get it.
In short, GUIDED WALKTHROUGHS.
Other possibilities:
Competitions with voiced commentary and thousands in the crowd.
It would be cool if they had this system where, while watching a game, you can "connect" to a friend or friends who are watching and the connection acts as a kind of digital loge. You can hear your connected peers at normal volume, but you can also hear a muted crowd in the background. So, say you're watching Starcraft or something. During the game, all the chatter blends together but then at a crucial part of the game, everyone stops talking and goes "OOOOHHHHH". It would feel like being in a stadium.
The guy in the video said it would be something like this.
This really is the future.
I can easily see this becoming something like network television. A true gaming channel.