Technical name for this? (PIP picture in picture with transparent background via green screen, chroma key) Two questions regarding this screencap:

http://imgur.com/RYIBdo1


What's the technical name for this? (where you impose a PIP that contains transparency, via a green screen, so there's no rectangular border)


(reason why I want to know the technical name: so that I can search for that feature while evaluating alternative video editing programs.)


What FLOSS (free libre open source software) programs for Windows PC platform are out there that will let me do this? Portable programs will get first attention from me.
The technical name for this is a "bug". Usually the context is that it's an advertisement for another show on the same network, or it's a network logo rather than part of the content.
I'm not very familiar with Windows software, but Shot Cut is free and includes compositing functions.