It was indeed a sequencer (of sorts).
Obviously an RB3 keys chart would have to take that into consideration.
Thanks for the link... I was thinking years ago that it could be played by a human with relative ease if a proper delay effect was used to duplicate the notes. Then your link made me want to search YouTube a bit and I found this:
Never mind the guy singing, but otherwise he's doing a good job with all the instruments, and he's really nailed the keyboard sound to make playing fairly easy