Rockman 4 Minus Infinity is the most extensive Mega Man 4 hack in existence, and probably one of the most extensive hacks of any NES game in existence.
It features heavily reworked weapons, brand new weapons, new items, all-new boss patterns, and brand new stages with new music and entirely new gimmicks. All kinds of obstacles, enemies, bosses and minibosses have been taken from other games from the series, including the Game Boy series and even the SNES and PSX games. It must all be seen to be believed.
This run improves the predecessor movie by the same author by 00:08.72 seconds, despite switching to a new category, "all items". This is largely due to extensive use of zipping to skip some boss fights. For more details, see the submission description and discussion.