I been saw Nam-June Paik’s
“Good Morning, Mr. Orwell” , “TV Garden” , and “TV Fish”
In those 3 works, we can see some scenes like remove background with Freeform Pen Tool.I’m just start to do Video Art so that I don’t know perfectly and sill little bit hard to understand every process of Video Art… But I really want to know his technique
Cat FULL of GHOSTS has a nice tutorial on a Edirol V-4 Mixer. At 5:27 he starts to describe the chroma key and luminance key buttons. I think this is the effect you are looking for.
V-4 mixers are fairly cheap and also a really great mixer but not necessary to do this effect. You can find luma key and chroma key options in mostly every video editing software. I use Davinci Resolve, it’s free.