This is just incredible. And, as far as I can tell, absolutely legit. Dark grey blocks make Mario run until he bumps into something; green Yoshi blocks make him jump, and pink Yoshi blocks do the same but make a sort of twit-twit sound; he bounces off note blocks, with a different sound effect depending on which side he bumps into; and everything else are just standard Mario game mechanics and sound effects (still trying to figure out if Mario is walking or just being moved forward by conveyor belts when he’s not running). There is absolutely no player input once the stage starts.
The whole thing is timed to the Nico Nico Medley, which makes it extra awesome. There are some pretty nifty details too, like the heart turning off in the “Marisa Stole the Precious Thing” section. It has to be seen (and heard) to be believed. So here’s the YouTube embed, and the Nico Nico link after.
組曲『ニコニコ動画』 全自動マリオVer @ YouTube:
組曲『ニコニコ動画』 全自動マリオVer@ Nico Nico Douga: http://www.nicovideo.jp/watch/sm3198603
Hope you all enjoyed that as much as I did.