Yeah, that's the point. Kaizo Mario stages are about rote memorization, building muscle-memory, and near-perfect execution -- it's a brand of levels that aren't for everybody. Of course nobody is going to clear it on their initial encounter. There are a billion other levels where that's the design philosophy.
At any rate, that's awesome that he finally did it. I can't imagine the relief.
Holy shit, props! Haven't followed this level recently but a while back I was checking the periodic videos updated with his progress and it was pretty amazing seeing how every video he got a little farther, and always disheartening when it was apparently super close, but no cigar. Seriously insane dedication.
I've seen a fair bit before, but NEVER to this extent. At 1:45 - Activating a block with a flying fire flower, then twirling it right to throw it in the noteblock and activate a vine, and still avoid it on the way down? Downright madness, haha.
That might be one of the craziest videogame-related things I've ever seen. There is just an unbelievable amount of bullshit crammed into that level, congratulations to the creator for finally conquering it.