I mean it's technically possible now, although it could barely pass as a "video".

It's like everything take self-driving for example. We had self-driving cars doing 99.9% of driving by AI back in 2004. Since then advancements were massive, but for a regular person it's probably still not exactly what we could call "self-driving".

I think a better definition is when AI will be able to make a movie that can create comparable revenue to Hollywood blockbusters.

So to your question I'd answer "today", but in my more strict definition of it I'd say 10-30 years.