In this video, I cover getting all the Teensies and Cups for the "Swimming with the Stars" level of the "Sea of Serendipity" contained within "Back to Origins".
This is a long level, though fortunately it's not too hard so long as you are slow and cautious around the spiky amoeba-esque plants. It also happens to be a somewhat scary dark level, and I think the Legends enhancements have made it even creepier than it was in Origins.
0:56 - I recommend that you retract this plant before getting any nearby lums. You might get hit by the spikes if you don't.
3:49 - These cheerful hidden areas didn't get any less congruent in Legends. A shame that they didn't consider revising it to make it fit better.
8:02 - My overzealousness in getting some mushroom lums caused me to screw up getting five extra lums from an extra heart here, but it's not a major loss. I'm already quite a ways beyond the gold cup requirement.
8:43 - Even brief exposure to darkness is dangerous, as you can see here.
10:03 - Oh yay, another water level to take care of. How fun. :/