I don’t see an easy way to search for “posts with some kind of video embedded”. I think that you might be able to do a data explorer query for something like
SELECT id post_id, topic_id from posts where cooked like '%lazyYT-containers'
or cooked like '%inline-onebox%'
and get the posts and topics with some kind of embeds. You could refine it further to get just the ones that have things that you think you care about, and then, I think, you could have a theme component pull that data explorer query and do . . . something.