Can anyone help me understand what’s going on here? https://youtube.com/playlist?list=PLTbUD6p8M0z9R-AZFCbdPvRHJlwBzePLl&si=dk7tS_KlrEH92Ve9

This is what Simplistic6502 said:

That’s very interesting. I wonder if one of these levels is actually playable (not getting stuck in the ceiling,) but I’m not sure.

I know for smb1 there is a game genie to move Mario even while he's in the celling so there might be something like that for this game.