Hi, I'm just curious how people can speedrun bullet hells. I was under the impression that there was no possible way to speed up the game since it was an auto-scroller.

In the bullet hell titles - the bosses have a specific attack patterns (non-spells and spells) which are timed events. If you can clear them faster by using bombs and/or correct positioning, you can cut time. (NS/SC optimization) There is also a ton of resource management, different games have different ways to gain lives and bombs. So the better resource management, the better NS/SC optimization.