Indeed I did enjoy these vids - a lot of my work is with live reactive/interactive visuals. Here's an (old) example:
https://vimeo.com/223696125Usually the performer is facing an audience with the main screen behind. I've found the biggest challenge is to arrange a second screen so that the performance is truly interactive rather than just reactive to their movements. When this isn't possible during performance to a live audience or straight to camera, time needs to be allowed for rehearsal of the movements.
I use infra-red lighting and cameras for the video feed to Magic, so that the movement-detection camera doesn't "see" the projection. Are you doing the same?