Thanks for sharing that video - thats the best explanation of the optical compositing I have ever seen!
I'm very interested in that process, because I work on a small project trying to replicate the Bladerunner look - which was done with the latest and last optical compositing. There is a bit more to that look so... but understanding every step is vital to the final image.
It looks like you're new here. If you want to get involved, click one of these buttons!