I guess there's filtering for something beside interest in the functionality, 55s into a 1m44s video before seeing the interface is not good.

The concept sells itself for those interested. Instead of just twitter, in 3 Windows in each of 4 Spaces, apps (or at least differing websites) with matched purposes, or themed background colors, should be used for the demo. Don't bury the lede -- more than halfway into the video introducing it.

1) show what it offers, 2) show how apple's native spaces falls short.

I think people can give spaces names, so showing that name might help with maintaining their workflows.

Time-cost costs users, costs revenue. Good luck!