Well friends here is a usage scenario for your consideration. I was invited onstage with Penn and Teller as a witness for one of their most unique acts, the "magic bullet". They saw me with Google Glass and Penn asked if it was recording. I told him it was not. He told me to turn it on and just to confirm with his partner that it was ok he asked Teller, who replied in the affirmative. The result is the video I have shared here.
I have quite a bit to learn regarding field of view during recording, but still this makes for a very interesting and enjoyable video.
So the use case to consider here, is one of documentation of live scenarios, including, when you have permission, acts of great entertainers like these.
By the way, both Penn and Teller tried on the Glasses for the first time after the show.