Start with Danny Elfman's Batman theme + Heavy Metal + 8 bit platformer = Epic Fun!
I have not laughed that hard in a really long time.
Did they stop at Batman? No! They covered all the classic:
Their cover of the X-men theme is amazing, and the Transformers, wow. I feel guilty I didn't know about this sooner.
Thanks to Badass Nerd for sharing the video. This is in rotation for me now.