Three words
Re play value. Ok, that was 2 words. But you have a great concept, characters that complement each other nicely and above all else, replay value (I've watched this 4 times now). The video game cuts are much better than the live action pizza, which wasn't bad and I like how you cleaned up the other scenes like Grim's exodus from hell and Croker's creation. The only two things I would work on are Stacy's voice and the 'South Park bounce' when they have to move.
This is really unique, I hope to see more!