Thank you for playing, and for the video! I noticed you didn't use the special attacks that your characters have, so that may be the cause why some levels were a bit challenging. 3D mode was definitely just a fun idea to see if I could get that in, and I agree that playing it is much harder that way lol
For the music, I basically listened to the original track and copied the notes of the main melody, bassline and drum pattern for most of it and as best as I could, then assigned my own instruments, additions and details to it. There's another track playing on level 5 (or 6? can't remember) and on the bossfights at levels 8 and 10, which in my opinion is even better :D