In this video, I cover getting all the Teensies and Cups for the "Fire When Wetty" level of the "Sea of Serendipity" contained within "Back to Origins".
3:08 - Once you get to here, you're going to have a pretty hard time keeping up with the speed at which everything passes by. As you can see though, it's possible to get the 300 lum requirement for the gold cup even before entering that part of the level.
3:51 - I still wonder what the hell is up there. It's not a flat wall but rather a lightly sloped platform, and it makes me think something is up there even though it's not accessible.