Almost everywhere that accepts user generated content has T&C along the lines of "you grant us a perpetual license to use, store, transform, and share whatever you post" just so make sure nobody sues for the normal boring use of showing it to other people.

That phrasing probably covers this use, too.

My guess is that he is protected in several ways by post-training.

Just googling around, it's worse than I could have imagined. For a few bucks/image you can make your own videos with pre-baked prompts or even custom prompts.

At a few bucks/image they must be making bank. This is probably a huge industry.

My kids have to grow up in this world