Haha neat idea :) Can't you simulate this in git?

  1. git checkout -b demo
  2. write some code and/or comments
  3. git commit -am "message of what we did in this step"
  4. Go to step 2 if not finished with demo.
  5. Cycle through commits with script, each one a frame.

I probably didn't think about it enough (commit granularity too fine == annoying), but that seems like it might work, and you have the added bonus of having everything in git.