Maybe our education system is a bit archaic compared to the states; I don't know, I've never been in a class room in the states.

But yeah, somehow I think being disruptive enough to get thrown out a class and then thinking it was a good idea to post a video of the altercation with the teacher on social media was a pretty big breach of conduct. I could completely picture the same altercation happening with a friend of mine harassing the R.E teacher with the flying spaghetti monster. I'm pretty sure if he recorded it, put it online and it went viral he'd be expelled. There are so many avenues that you can take to address a problem in a school that it's quite clear he was doing this for attention. Not to mention Scottish education is tiered. A movie that shows this is Neds (2010) which stands for non-educated delinquent.

If a student starts acting out and disrupting classes, they go down a rank from credit -> general -> foundation -> special needs depending on the severity of the problem. Expulsions generally happen when the issue is so severe that it requires a special institution.

But no, you don't have a right to record your teachers and if it ends up causing them and the school grief, you're absolutely responsible for what happens.

I honestly don't care about the content of what's being discussed and that seems to be the only motivation behind why this got traction. It looks like a modern studies class; when I did modern studies we discussed American politics for a month which involved a short introduction into American political thought and the teacher showed some parts of Bowling for Columbine and other conspiracy theory videos. It wasn't about trying to teach the kids about 9/11 conspiracy theories, but presenting modern political issues from abortion to gay rights. If the content can trigger you so much to warrant the teacher throwing you out, then yeah. Teacher is 100% correct for the kids who want to learn and get on with their school life.