It's not a single video (and sadly there hasn't been any new content in a year!), but [Richard Borcherds's channel](https://www.youtube.com/@richarde.borcherds7998) has some of the best math content I've seen. If I have to pick one I'll go with [this video from his Rings series](https://www.youtube.com/watch?v=DuQcj3GdayE0) about Burnside rings and differential operator rings as an illustration of his style; for me, at least, it's a source of excellent insight into fields (*cough*) I know very little about.