In basically all cases course material is developed by professors and TAs, though the current lecturer might have adapted from several years of previous work. W

In basically all cases course material is developed by professors and TAs, though the current lecturer might have adapted from several years of previous work. Who owns the IP exactly is tricky (likely the university has at least an equal stake?), but I expect that if lectures are recorded, but not open-access then it's the lecturer's decision. It might be copyright issues, re-use of someone else's slides, not wanting to let students see past years' work, etc. For example, I work at ETH and we have a large internal video archive of lectures (as do many universities pre- and post-covid), but some lecturers choose to post material on YouTube too. It's not a blanket yes/no policy at the institutional level, as far as I'm aware.