Firstly, this can only be done with mr. stick. I should preface this because any time you try to do these exact moves with a different character it just doesn't happen whatsoever no matter how much you try.
With that out of the way, you first need to do a mach run then turn it into a superjump, specifically while going right.
Then, After that, cancel out of your superjump using the grab button
Then after that, cancel out of the dash using jump.
Before falling to the ground, pause. Make sure not to do it way too early also, you may pause during the fly cancel state, but still not get the bug if you did it extremely fast. Also don't do it while in the wrong state, sometimes you can just do it too LATE such as when you hit the ground before pausing.
Then after pausing, hit restart level. After that, you should have skipped the door animation COMPLETELY and can immediately start moving.
Congrats! You just did the level gate animation skip!
