Ain't this a nice idea, i'd watch that.
One note though: If the commentary is also supposed to help the playing players, you'd probably need save the stream so that the playing players can watch the commentated replays when they're done playing.
Another possibility would be to put the players into the same conversation (be it skype or whatever) as the commentators. But, depending on the level of seriousness, the players might be too focused on the game to listen to anything. So yeah, replays would be good