Edit Video Like in Star Wars ?

[SEJedi]

Years ago in the remaking of the Star Wars movies, the alien figures that was played by masked humans, were superimposed by CAD figures, with alien skin and whatnot. As much as I know, it was done by giving an input to the beginning frame of a sequence, and the software would remake the whole sequence.
Question [1]
I ask if anyone knows with which software and how to replace the whole figure in video. I know there is software for remaking whole sequences, I just don't know which is good enough.
Question [2]
Another thing would be to change the skin texture in, say, inch deep, then I could already change the actor into an alien. Naturally, also for whole sequences.
--- If there are any video-savvy persons out there, please, let me know.
NOTE I've tried several video forums, but got stupid replies like do each frame with photoshop. With a 30-min video it's almost 50,000 frames. It seems many people don't realize the difference between still image and video.

[Skyman]

Unless you are using actors with markers to pin the wireframe 3d model too then photoshop rotoscoping is indeed how it is done. You could import the footage into a 3d ap and use the actor as a guide for animation your 3d model then export the model and superimpose them on the film. You will have to carefully scale and mask the model to make it work with existing footage. It helps if your continuity editor has helped direct hots with 3d in mind but basically the star wars remakes with animation did it the photoshop way, but they had teams of artists to make it work.

Far far easier to shoot in front of a green screen and composite into your landscape. That is what most productions do. I don't know that the software to do it is available for small scale stuff and it basically requires a server farm to run it.