This is the book: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.maa.org/external_archive/devlin/LockhartsLament.pdf
I was sent a link to this video after I complained about math teaching, and it took me a couple minutes to realize I was familiar with it and that I had even quoted from his book here before.
This is the video:
Probably the most contentious line in the book: "Many a graduate student has come to grief when they discover, after a decade of being told they were 'good at math', that, in fact, they have no real mathematical talent, and are just very good at following directions."
