o.0 That video is horrible, it feels like it belongs at the beginning or end of a movie where a dude loses his collection. Also, a "demo" would be one using the Neo-Geo hardware to make music and visuals off it, not a video featuring it.
This might be better o.0 :
But I can't find out if the chiptunes actually were made with Neo-Geo hardware.
AFAIK, just like making AES or MVS carts, in order to get music to be programmed for it, and run through it, you would need a donor cart. The closest you could get is something that made music off splicing random sounds from the game itself.