btw I actually start finding this out at around 1:20 or so

so the gist of it is play though the game on a new save file, then exit out of the chapter when the level to level cutscene is happening on the selected level that you want, then delete the save file and create a new one, then bam the level is unlocked instantly from the start (the levels have to be in the time frame of the opening cutscene in chapter one). (from what I know so far this only works on chapter one)

uuuuuuhhhhhh so randomly this happened

I have no clue why but randomly while I was playing through the game it just skipped a bulk of the levels in chapter 3. I do not know how to replicate it and its only happened once in chapter 3 and once in chapter 1 (it only skipped the first 3 levels in chapter 1)

idk if this will be helpful for speedruning but I just find it odd