There's actually already an autoplay mode! It's accessible through the console. Details here : https://github.com/bunfan/beat-banger-public/wiki/Console-Commands
Though we'll probably implement an official gallery mode in a an update.
I think a Gallery Mode would be really nice. Not only would it give us free hands to work with, but (for me personally) I like earning the scenes at least once before going completely hands-free.