Again, thank you very much for those fast and clear replies.
Great idea about the Commodore and Atari games!
I will also continue to check for the pictures in Jinn's repository.
Indeed, the proposed algorithm will not perform as well as an artist (I'm 100% sure of that) and -as you mentioned- hiring would reaaaally be the best option. However, I'm afraid that it's way to expensive for our short budget (it's a music video about 3/4 mins long).
But when we will be signed to a big major company we will hire a bunch of artists for sure! I would loved to have a pixel-art music video clip, it's really beautifull