make a sound and depending on the loudness of it the face changes. And a background for videos or games to react to. tip: go to a quiet room to record so background noise doesn't get in the way. The green is just there to line up the video with the lines so it doesn't cut off any parts. It's the most noticeable color in my opinion. tip: add the video and change the green background to black screen record the video that you're going to react to and record the sound at the same time so they're linked up.
