I watched the video and I'd like to say:
The song should react more to the track. Beat detection seems to be there. But the track shape itself it doesnt react enough to the music.
Audiosurf reacts on slopes even with slight variation of speed and intensity of music. In your game it seems only react to a slope when the song has a bigger variance. (from very slow to very fast situation)
So it looked like in the video.
And there should be more variance in the powerups. In the video that are all that green ones. Add more colours with different scoring and maybe some other stuff. So it is more challenging.
Sound was already said by the other and the effect when you collect them should be changed. It should be more decent. currently with its flowing up it bloats the screen.
I also have to say, I'm impressed how much FLAC users we have here

I'm a fan of FLAC files too
