In the spirit of expanding our knowledge, I hope to hear back from the Hacker News community about the lectures or speakers you all find interesting.
Sapolsky's lecture on depression in the US [0] got me hooked and now I'm working my way through his Human Behavioral Biology class[1], which is also excellent.
[0] https://www.youtube.com/watch?v=NOAgplgTxfc [1] https://www.youtube.com/playlist?list=PL848F2368C90DDC3D
Anything by Feynman. There are quite a few of his lecture courses online, on various subjects.
Hamming's Learning to Learn course https://www.youtube.com/playlist?list=PL2FF649D0C4407B30
Anything by Gilbert Strang, he's a great teacher. e.g. https://ocw.mit.edu/courses/mathematics/18-06-linear-algebra...
Youtube videos by Vi Hart, tech talks by Julia Evans.
In the art world: any program/series involving John Berger (Ways of Seeing) or Robert Hughes (The Shock of the New).
Documentaries of Patricio Guzmán and Werner Herzog.