It would be allowed but there are the keyboard A key to skip the replay and go to next level, S key to exit level skipping the replay.

So no need to bind both jumps on the same button.

I had something like that on a very old PC that had a poor graphic card

Yeah it's a known thing and it's called a storage jump. When you die or finish a level, your character's position is kept in the game's memory. When you start next level, you start with that same position for one frame. For example : if you were touching a wall when dying, you'll restart the level in a walljump position. If you don't touch anything when dying/touching bandage girl, it won't work.

Nice you found that by yourself

For example, if your game is running but you're on your browser, when you alt, it will alt on your browser. Not in the game.

Alt works on 1.2.5, you can even do the ceiling clip. It works differently but it works.

Did you make sure your window is selected ?

iirc it teleports you to the same coordinates as the previous level you played. Not sure tho

Or it could be this https://www.speedrun.com/smb/thread/qmwfs

Everything is explained here

Level Leaderboards > Select your chapter > Individual World

GG ! :)

Nice work !

Je le connaissais que par son pseudo mais ça fait bizarre à apprendre. Toutes mes condoléances à tous ses proches.