No miscommunication: This project is amazing.
From the Youtube page:
Features two 3 1/2″ drives and two 5 1/4″ drives connected to a PIC18f14k50 microcontroller. It interfaces to any MIDI source via MIDI over USB. Straight MIDI would also be possible with an additional small circuit and some minor firmware changes. This initial version can respond to all 128 MIDI notes, and pitch bends +/- 2 semitones.
As it can produce only four simultaneous notes, and each drive has a different range and tonal characteristics, best results are obtained by arranging compositions by hand. However, it features two modes of operation: in one mode, MIDI channels 1 through 4 are played directly on floppy drives 1 through 4. In the other mode, all 16 MIDI channels are read, and notes are “intelligently” divvied out on a first-come, first-serve basis. “Note stealing” ensures that melody lines sound, but chords are often cut short. One or the other produces acceptable results for many unmodified MIDI files straight out of your favorite media player.