This video is projected on a large screen behind the performers. Performers are supplied with a library of video segments, audio segments, etc. which they play in response to what is happening on the big video. Every aspect of the scene evokes a response. One performer controls the mixing board and keeps the sound reasonably intelligable. Another might also control the lighting or switch between video segments if there aren't enough monitors for everyone.
Performers are familiar enough with the main video and their own libraries to make timely responses.
The main video is not pre-recorded, but is done during the performance.