I must say, this is the first time I've ever heard 'Crazy Train' using a banjo and mandolin...and other random objects.
He gave himself 12 hours to learn the song and chords, and this is what he came up with. From the way it sounds, it was a productive 12 hours!
I just felt my self-esteem lower a few notches after that.
But really, check out the banjo solo at 3:12.