I recently signed up for MasterClass, as there were more than just a few people giving courses that I'd love to hear from. I started with Steve Martin's course on comedy. I don't think I learned anything specific that I'd call out, but I did get a solid overview of his thought process and I found it very enlightening. I then took Shonda Rhimes Teaches Writing for Television, and found it even more useful, as I'm working on a television screenplay (don't worry, it's for fun. It's going to suck. But I want to do it).