Last week MetalSucks posted this video of The Avett Brothers on Late Night with Jimmy Fallon doing an infomercial-type segment of a bunch of heavy metal covers like they're folk songs.
The joke loses it's muster after a minute. The covers are just too smiliar and boring after they get onto Black Sabbath, which is the second song. So that should tell you something. Still, check the video out at least once for a good laugh.