Since “Imprimatur” literally means “Let it be printed”, I would think that would rule out videos by the very definition of the word.
I don’t see any bishop granting an imprimatur to an ongoing series (print or video) for the simple reason that the author could at any point in the future say something that is not in line with Catholic teaching. He can only evaluate what is already there, not what may or may not be there in the future.