Math-wise, I have no idea how many things are being done in a demo like this. But it rarely surprises me. What I love to see is the Atari doing things, and I can't understand how they got it to do it. That always makes me gasp. This demo made me gasp multiple times. Bravo!
Well, not bad, not bad at all. You can do it better though :) Music starting at 14.00 - this is my music :) I mean, I would do the same. Very, very nice put together.
On your channel the demo is displayed incorrectly from <a href="#" class="seekto" data-time="199">3:19</a>, because Altirra has a bug. There should be no horizontal blue lines visible.