I've been a fan of TAS (Tool Assisted Speedrun) videos for a long time, and always go back to watch the various Mario 64 Speedruns because they're so good, but after watching a few videos, I wonder:
Why are the keys obtained from Bowser even necessary, when the speedrunners have the ability to slip through walls and "locked" doors (that is, doors that are locked off due to not having enough stars)? What's stopping them from Backwards Long Jump & Running their way up to the final Bowser fight?
I originally suspected that the layout of the keyed door and adjacent walls up to the third floor meant that a BLJ & R would be impossible (due to there not being the "right" kind of gap to pilot Mario through, like the Dire Dire Docks water wall or the original BLJ & R that took Mario into the first Bowser level), but now I'm not so sure.
Anyone know of reasons why a "no keys" run hasn't been done yet?
Best Answer
The reason why is because the castle is split into multiple zones (ground floor, basement, and upper castle), which are not loaded at the same time. Like the outside of the castle is a separate zone, and glitching through the door won't actually bring you inside the lobby.
It is possible to get behind the key doors, probably even without TAS, but there is simply nothing there. You have to activate the door to load into the different zone.
The reason why you can skip the first key as you showed, is because the basement has a second entrance, which is not locked. Normally you can't activate a door while underwater, but if you reach the door before the game can register that you are swimming its possible. The upper castle only have one entrance, so this trick can't be used here.
I'm not aware of any glitches where you can load into a different zone through a locked door.
If you are interested in these kinds of technical glitches, you should check out pannenkoek2012 and his second channel on youtube.