It doesn't necessarily have to be live action. Using 3D models, draft sketches or even stop motion you could create whatever "base" necessary for the AI to build upon to make its final product. Lets say for example that rather than a big company im an indie artist, i might just hop on a video game like second life or something, act out and record the stuff i want, then ask it to overlay a different "actor" doing the stuff on top in a different art style.