Ask HN: Can you ID this video?

I likely watched this video right after it came out and that was likely around four to six years ago. I most likely found it via HN, which is why I am asking here. I believe it was a speech at a convention, possibly PyCon. The speaker was a man with a long beard that he braided into two braids. This seemed to be kind of a personal "trademark" and he had apparently looked that way for some years already. As part of his speech, maybe a speech about math and programming or math and Python, he told a personal anecdote that goes roughly like this: He used to teach on a reservation and he lent a math book of his own to a Native teenage boy and the boy got beat up real bad and quit school, apparently over having accepted the math book from a White man and taken it home to read it. The boy returned the book to him at some point. Years later, he noticed funny stuff in the margins and was able to identify it as the boy's Native language and found a way to translate it and the boy was grateful for having read the book in spite of the high price he had paid for doing so. I think the Native boy referred to the speaker telling this story as something like "Two Beards" in his notes in the book. This may have been a keynote speech. I spent maybe an hour looking for it last night and I'm stumped. I have no idea how to find this and I would like to rewatch it. If you can post a link to the video or tell me who the man is or something like that, I would appreciate it.