That’s the clue I used, but I didn’t find it very obvious which “Graydon” the URL referred to. I’ve never heard of Graydon Hoare before but he seemed to match up with the content of the slides. For some reason he seems to be intentionally obscure about who he is on the website, but I see now that there is a link to a named Github profile.
Funny you say that because he's done exactly that! If you look at http://venge.net/graydon/talks/codecon-2006.pdf about Monotone, it turns out (see http://venge.net/graydon/talks/) that it's “A talk Nathaniel Smith gave and I sat on stage looking supportive for, answering occasional questions. It's close to what I would have said!”
(Nevertheless about the original question: yes it's by Graydon Hoare as he mentions: “Talk for some undergrads in computer science at UBC about the wide world of compilers.”)
Edit in case it wasn't obvious: it seems unlikely that Graydon Hoare would upload someone else's talk on his homepage together with his other talks.