@adz
cromakey, is a technique "similar" to the one used by Amiga genlocks bui it uses colors instead of color 0 of the Amiga palette.
Usually for video works, the color is a green (greenscreen) and in film works it is used the blue (bluescreen) fot the backgound.
The most important thing, are the light positionings in the scene. They doesn't make shadows on the backgound screen.
Now, there are some way to use Chromakey.
If you are using a NLE program (Amiga few, PC a lot), CK and LumaKey are possible using its internal apps options.
If you still use an online system, there are available some very good video mixer, that can do the job.
The best option, is to use an harware RGB cromakey gear, with the possibility (very important option) to smooth the edges of the foreground.
Ciao
