Fan versions of songs are wiped from YouTube faster than anything.
It's possible a cover could be done in the new series if it's in the public domain. As songs in the new series have ripped off the direct tune and melody of several songs so far (Eye of the Tiger to The Beast Inside and Wake Me Up Before You Go-Go to Awesome town), I see no reason why they couldn't cover a public domain song. Wham!'s other half and Survivor haven't sued yet, so if the singer is obscure and it's not in the public domain yet, go for it.