Seems like a neat idea. To make it seamless would be a bit of a bandwidth challenge, because if you've got four different cameras, you'd have to be buffering (in at least some capacity) four different videos simultaneously.
Conceivably for concerts, you could stream four video feeds, but only one audio feed, and that could prevent audio stutter in transition (which would be the most obvious) since the audio feed then wouldn't change. But saving that audio bandwidth isn't going to mean a lot weighed against four 1080p video streams, I guess.
I'm with you dstarr3, but they probably only need to buffer all streams if they want immediate stream-switching, which doesn't really seem necessary - when is it critical to have a different view *right now*?
They could respond to the user input with a little "switching" notifier, and start buffering the chosen stream while continuing to play the current one. When the new stream is ready to go, make the switch.
Anyway, that doesn't sound as bad as an audio stutter.
I could see this working really well for racing sports. Getting different angles from one car would be really cool. If it got to the point that you could switch between the competitor cameras as well, that would be pretty awesome.