I thought Steve insisted on doing as much as possible from the mac itself. Even if most of it was 'just a video' and the music was external.

So it might be very well the Mac itself the screen was hooked up to.

EDIT:

Via folklore.org:

http://www.folklore.org/StoryView.py?project=Macintosh&story=The_Times_They_Are_A-Changin.txt

http://www.folklore.org/StoryView.py?project=Macintosh&story=Intro_Demo.txt

In short a board was made by Burrell inside the Mac to display.

Click to expand...

HAH! You beat me to it :lol: