41 Strange

You sure this isn't a fucking green screen mask

If it was green screen wouldn't the face just be a black shape instead of transparent?

Not if the background is a picture of the same room

Ah, of course, the background is stationary. Doh! What still puzzles me is how they shoot, say, a person with a missing (chroma) limb in a steadicam shot. Do they actually shoot the background right down to the slightest cam movement? It can't be that as it seems near impossible.

Maybe you have to let the system analize non-moving things to know what should be replaced, like a kinetic system, analizes movement, but I don't know this is beyond technology, this is fucking black magic

Ha! I know. Recent example was the woman in Mad Max: Fury Road. She wore a chroma glove on set which was then replaced with a robotic hand. That cam was all over the place in that film, yet the backgrounds (through the hand) are in perfect sync. You're right, black magic!

This has nothing to do with the thing but mad max: fury road is my favourite movie

isnt that just greenscreen

If the foreground object is moving, it can infer what the background should be in all the frames, and because it's a "face filter", it substitutes the background for one's face while adding blur and partial transparency effects - green surface not necessary.