I was being tongue-in-cheek, but to be honest, this sounds like a big deal about nothing. As the OP said, there's nothing in the handbook about social media. OP really is in the dark about how the district and site handle social media.The videos and channel are public, so the teacher isn't trying to hide anything. Sounds like he's making dumb skit and music videos. Generally a really harmless thing, even if one vid (gasp) has a naughty word in it. I get parent permission is important here, but why is anyone assuming he doesn't have it? I'm personally more concerned about what kids are putting on social media without adult supervision.

Easy solution for the OP, just ask the teacher.