I hadn't thought about the effects of his old nearsightedness, but wow, that seriously might have something to do with it. Still, Al didn't seem very put off by it and the way he played it off probably doused the "embarrassment factor" quite a bit for himself and anyone watching that video.
... Al should definitely try overhand though. That alone would've stepped up his game. A lot.
I've Seen Weird Al In Person:
8/26/08, 5/22/10, 7/15/10, 7/16/10, 7/17/10, 11/5/10, 9/22/11, 9/24/11, 9/25/11, 4/30/12