Hey, it's possible today.

My wife and I were on a cruise a while back, and this duo was performing. The guy was on a conga drum and this hot looking chick was playing keyboard, or so I thought. The guy was a pretty decent singer, but the girl's hand action didn't match up to the music. I went out on the deck and around behind her. Yep, she wasn't playing at all, just faking it.

The real pity is that, I bet, nobody knew the difference. I can see using sequenced material, but hey, do something musical on your own.