When I saw this video, I did think "Surely, if you're doing aerobatics, then you want to see what's in the sky, not a bunch of mates on video chat, so having a chunk of your peripheral vision taken up with a display showing something else would", I thought, "be a pretty bad idea."
Although of course the real problem will be hordes of people in the streets shouting "OK Glass, do *blah*" - it'll be worse than people going "I'M ON THE TRAIN!".