Warren Buffett is nothing if not a disciplined investor, and he explains that his visit to the Alberta region was for information gathering only, something that he will file away and may use a few years from now. As he explains near the end of the interview, he's now gained knowledge on cost aspects of the business, but the biggest wildcard remains the longer term price of oil.
Note that he already holds $1.5 billion worth of ConocoPhillips stock, which claims to have the "largest position in Canadian oil sands".
It's mentioned that they visited CNQ's new project as well as an unnamed SAGD (steam assisted gravity drainage) site. Since COP has a joint venture with Encana (ECA), and since Encana has SAGD sites in production, my guess would be that they visited an Encana site.
CNBC: Buffett/Gates Energy Tour.