On the 3Blue1Brown channel.
Written by: Stephen Welch, with very helpful feedback from Grant Sanderson Produced by: Stephen Welch, Sam Baskin, and Pranav Gundu
Post-lunch food coma was getting a bit hard to focus at the end.
But the animations make it all much more intuitive, as always.
EDIT: The Welch Labs channel seems to have a lot of interesting material, especially on AI stuff.