Damn! Someone beat me to the "critical list" comment.
I once saw a video on YouTube with Brian at the piano attempting to imitate Mike's singing style circa 1979 or so. Al is standing next to him and he asks (a very embarrassed) Al to hold his nose while he's singing -- which Al does! I wish I'd earmarked this video -- it was hilarious.
It's on the Endless Harmony DVD
It's from 1996 or so. The Stars and Stripes sessions.
How could someone possibly mistake a 96 Brian for a 79 Brian? They practically look like a different person. (Well, as most people do over the course of 17 years)
Because I saw it only once in a fleeting moment over a friend's house circa 2006-07. Plus, I associated it with another video we were watching of the 1976-era Brian at the piano singing "I'm Bugged at My Old Man" with Carl and Dennis on backups. That one is still on YouTube.