Virtual Backgrounds offers a physical, pre-camera solution to a virtual background. The traditional method would require chroma key and some sort of a switcher. Their solution uses a camera mounting system and a projector that projects the image into their mirror and then composites out the subject against one of their backgrounds. It did remarkably well as you can see from the video when I put my iPhone and Canon Vixia through their device. At about $5000 for the camera rig (including projector) (background material required and sold separately), I’m guessing that it might be simpler than using a traditional keyer/switcher system. Also, worked well considering there was no special lighting required.