I'm seeing the same thing here. The frame rate in the fish-eye gameplay is abysmal, then the boss battles are running like a dream. That's no wonder SEGA wanted more of what was going on with the boss engine, than Ofer/Chris Senn's side of the game. (It sucks that POV beat them to the presentation, and they had footage of their PC version running perfectly.) Either way, these clean rips are impressive. A hat tip to Chris for uploading these for the rest of the world to see once again. I'm sure it's doing wonders for your research, Andrew.
Oh yes some of the background blocks have animated glitter textures hahah. you can still make that out in the old videos if you look closely !
If you separate SonicDemo96 clip into 60fps fields, they still appear two blended frames sometimes, loops in particular. Why is that? Was this footage, like, recorded with interlacing, then corrupted/blended and interlaced again?