Tom Scott Explains How Chroma Key Composite or ‘Green Screen’ Effects Worked Before the Age of Computers

In a recent video, host Tom Scott of the series Things You Might Not Know explains how chroma key composite effects, commonly called “green screen,” worked before the age of computers. Modern graphics programs can digitally erase a specific color and layer two pieces of video on top of one another, but similar effects used to be done with tricks of the camera, chemistry, or electronics.