It turns out that Zoom deletes all recordings after 30 days (thanks to the student who brought this to my attention!).
There are 4 recordings that are still available: On Network Security (will be deleted in 5 days), on the Link Layer (12 days), the Final Revision (19 days), and the Final Q&A (26 days). If you think these recordings will help you prepare, please go ahead and download them.
At the same time, I should re-state that the lecture discussions were not designed for recording so they are not exactly pleasant/easy to follow -- the lecture videos are better for exam preparation.