Yes, the video is real, but GT didn't tell you it was made with a disk drive controlled through the parallel port. AFAIK you can't do the same thing with the ST's internal drive directly.
The program to convert and play the music is one I made myself, but it's an abomination (messy source code, only works on PCs under pure DOS).
Also, most tunes don't sound good -- the range of notes that are "playable" on a disk drive is pretty narrow.
I'll try to find a little time to release a ST version, with instructions on how to hook up the floppy drive to the parallel port