I also watched on live (actually twice, cause my friend wanted to see it and had to work.)
It worked perfectly both time. I have Kinect on all the time, and never had a problem with the sound from the speakers effect Kinect.
I don't know if these people are foolin, or if they didn't calibrate or something else. Here is a good demo of the current voice controls:
http://www.youtube.com/watch?v=Xgfwt2O7VXQ#t=0m42s







