I love this concept! Having to multitask is actually quite fun, and I can see cool potential for different notes, or even having to control your scroll-wheel so that it's not always constant spinning! Or maybe a mechanic where you need to control the scroll speed as well? You could also do something where the direction you scroll will determine which way to record turns, and could do some cool things with reversing the song? There's lots of potential here!
I think some of the notes felt off-beat, at least the Pop SFX that plays whenever you play a note. It would have been really nice if that pop was on beat with the music, adding to the game feel and satisfaction! I also wasn't sure if there was any penalty to stopping the music. It looked like my combo was still maintained? Maybe having some sort of penalty to stop the music would add some more difficulty to the game, but for a jam it's perfectly fine.
Overall, really great job! The idea is really unique and fun, and you nailed the visuals and polish! Congrats!