I use green screen when editing my own personal videos. You can easily find green screen images with a simple Google search and use them on the highest track in a video editor like Sony Vegas. You then convert the green to transparent which allows a lower video track to become visable in just the area that was originally green.
Sounds complicated but it is actually quite simple.
I use Vegas Pro as well.
That is very interesting. I use Sony Vegas for my YT videos. No real need for the technique for what we are doing now but it is intriguing. Thinking about doing something new.