It definitely is an impressive run, especially since its not a TAS.
I don't know any hard-to-reach spots, as I'm not that good myself. :P Some of the spots you went to I was like, no really? XD
I guess one jump you could do is this one:
There is a secret room with a map of the disorder. You go there to activate an achievement. Normally you would go in from the bottom using the green powerup. It should be possible to go there a different way using very precise jumping. There is a secret passage where you use the yellow powerup to fly past some green lava which allows you to go into a new secret passage. You get a coin or something in an adjacent room. When you exit the secret, you fall down 2 rooms to the left of the disorder map room. It should be possible using jump and bounce techniques to bounce into the bottom opening of the disorder map room. I almost did it once, but I hit a wrong ceiling or floor tile that made me ruin the attempt.