An AI capable of creating a good movie from start to finish on its own has many more implications than just entertainment. This will put it very close to a general purpose AI, assuming we don't need a general purpose AI that can do this. A general purpose AI can do anything. It doesn't need a human helper to perform an intellectual task, it can always do it on its own. It could improve itself to make itself smarter, or faster, or think different from how it was originally created. Multiple general purpose AIs could work together, making them even stronger.

It will change everything and do so very quickly because it's software.