Adding a video in the background

You can do everything inside CA, except you can't import any video files. What you can try is to make a cycle puppet that uses images for layers, and position the cycle inside the tv screen window. I never thought of that before. I have made bar scenes with a tv showing, say, a football game. and the detail of the game is very small, so a repeating cycle might serve your purpose. If you try it let us know how it works. That might be a fun way to do it. I'm going to try it myself.

Edit: One way to do it might be to take an actual video and pick frames to make into the cycle.