that Cutss video is old and he is known for misleading people. When he was talking about that, the main issue they were addressing was the whole www v non-www thing. From my experience with some of the top SEOs I would say CasinoJack does a good job at addressing the issue in a minute for those curious people short on time.
Of course if you have an hour of free time, you can get more in depth elsewhere. Here is some more info and a good place to start: Official Google Webmaster Central Blog: Specify your canonical