You and @googlee had the same idea, thanks so much! I am now considering making this into a service.
Thing is, it'll take time (a whole lot of precious time), it's gonna take plenty of time, uh oh:
Haha, neat! The first object to "dance" is the clock -- and it does so aligned with the vocal "time"!!!
Ever since I (today) installed the plugin "YouTube ad blocker" -- YouTube has been glitchy, pausing each video about 10 times. It's doing it right now, as I type, and the song is half over! It should have buffered the whole thing by now. Guess they want us to use competitors! http://d.tube