I’m working through a course on Udemy on my macbook with bluetooth headphones. I’ve no idea why but the audio no longer works. Youtube audio is fine, previous lessons no longer have audio either, restarting browser has no effect. Disconnecting headphones makes no difference. Downloading lecture works, but is hassle.
Solution: In bottom-right, click the cog and change the quality from auto to a fixed quality (eg 1080p). This solved it for me. I don’t know who’s bug it is and I don’t care. I hope this helps someone else 🙂