I'm glad it helps. I think I said it already in the video but honestly if you ignore everything else I said and work on making the levels more like that one part I think you'll be golden.
About the combo meter and the flips, I tried it out briefly and it definitely does add something in terms of being able to get the meter up more frequently. Is it "enough" though? I'm not sure. It's sometimes a little hard to tell where you can or can't complete a flip (I think this might be more related to the flip speed being so variable), and while doing so is fun enough I can't help but think it's maybe a little too simplistic to be very interesting all on its own. Maybe if you added some other way(s) to gain combo meter too it would be nice. Maybe some different types of enemies, different ways to kill them other than just drive into them, and different mechanisms you can interact with on-the-fly. You've got the launcher springs for example but what about things that the player can use their given abilities to activate or get more of a boost out of instead of just working automatically or simply pressing a button when you're near it? Something to add a bit more skill and complexity.
I'm also feeling the effects of not having separate left/right and rotation controls more now (I tried with the default keyboard controls this time; I know there's the other method) since not only am I trying to get more flips in but I'm also wanting to like just hold right while I'm combo speedboosted for the speed and sometimes I rotate unintentionally. And sometimes I get flipped around from the direction I want to go when I land or something and I lose a lot of momentum and maybe lose the combo.
I think the idea of "perfect landings" keeping your meter up even if they don't give you the initial combo boost (similar to how you have it with the booster wheel things) is a nice idea, especially once you start getting the wackier terrain with loop de loops and things. For that matter, why not reward extra for flips that are landed "perfect" as opposed to "good enough?"
I'm sure if you get your combo thing feeling good and nail the level design this will be a blast. Also this is more thematic than anything but more things to get that "bear on a motorcycle rampage" carnage feeling would be great. I think you just need more destruction overall, and maybe crashing through walls and such could even work with your combo boost meter.