This is really awesome. I knew that CS3D had some crazy game-breaking bugs in it that had something to do with the inventory and map system, but I never knew the details.
The person talking in that video was a bit hard to understand due to the audio quality and speed of speech, but I could more or less follow along. That's pretty crazy how those different scripts got loaded, which enable skipping ahead to certain parts of the game, like skipping the Egg Corridor entirely, and jumping straight to Grasstown, as well as prematurely acquiring certain weapons and items. I was pretty impressed when I saw the Booster 2.0 get magically equipped, and then my mind got totally blown when that infinite life-capsule exploit got used.
It's actually crazy how many successive exits/reloads are required to pull this off in the quickest way possible, but once that person got the Ma-Pignon and teleported to the Plantation, then I started to understand what was going on. It helps to have opened this game up and looked at the scripts to understand what this person is talking about when explaining how this exploit works.
Shoutout to
@duncathan who made the donation that was mentioned at 20:50 in the video.
I'm a bit confused as to why the speedrunner did some more glitching around after defeating the undead core. Once you've activated that cutscene and have the Iron Bond, shouldn't you be able to enter Hell? I'm not sure why the player then went around and fought the Doctor, then Misery, and then the Red Demon, and then went around to a bunch of other places and fought a bunch of other bosses before finally making it to the final part of the game. Are there some requirements I'm missing, or was this person just showing off how thoroughly you can warp around through the game with this exploit? I think I heard some blurb about the correct balcony map not being loaded if you don't go around and do that stuff, but it didn't quite make sense to me.
In any case, this is a cool run.