Nice profile pic, End Cubing. Arbitrary Code Execution, or ACE, is manipulating the arbitrary (random) code of a game to do something specific. It's normally used to finish games much earlier than intended, but its purposes can be crazier as well. Some people have managed to write games into other games using the empty space in the code. Hopefully this was somewhat helpful. Cheers.

oh ok

He's back, you know.

I would actually also suggest in clips like 7-9 to jump pretty late (later than you think.)

Sometimes despite doing everything right sub-pixels will ruin stuff. Clips like in 7-9 I would suggest jumping as high as possible in the pipe. I'm not sure about the P speed stuff though, so, sorry. Hopefully this was a bit helpful. Cheers.