Rob Farley continues a thread:
The basic concept is that once you have a greenscreen application background in place, you can easily show text or drawings or whatever on the screen, superimposed over your webcam feed. I show how to do this in this post: http://blogs.lobsterpot.com.au/2021/01/30/presentation-trickery-online-glassboard-like-lightboard-but-using-just-free-software/. Scott Hanselman also made a video about it at https://youtu.be/-oaikJCR6ec, and used the idea to make scrolling credits, which is a really neat idea that everyone loves.
Click through to see how it works.