Introduction to Cryptography by Christof Paar: https://www.youtube.com/@introductiontocryptography4223. This is a great introductory cryptography course which is perfect to complement the great textbook from the same author.
I have been reading Matt' blog for quite long too. I read his post on his son condition but never really noticed if he really switch his academic careers for his son. I am pasting the really motivating video sharing the story [1] and a NY times article here [2].
I was writing (almost) daily email when I and my wife were in long distance relationship during the time my wife studied for her master degree. It happened just in the early days of our marriage. It was the day before WhatsApp has video call feature and long time before zoom. The small daily email quite helping us to form the bonding. Couple o lf years ago I dumped the email into this blog http://www.dearwifey.com/.