Looks like a good class; is it only available to enrolled students? videos seem to be behind a log-in wall.

Looks like the 2023 lectures weren't uploaded to YouTube, but the lectures from earlier iterations of the class, including 2022, are available publicly. For example, see the YouTube links on https://css.csail.mit.edu/6.858/2022/

(6.858 is the old name of the class, it was renamed to 6.5660 recently.)