A major portion of movies are visuals so watching it while playing a game makes it difficult to catch those parts. Also if I have to tune it out so I can concentrate in-game I will be lost when I tune back in. With a commentary video I don't have to do so because either I don't care as much, they'll repeat important information, or context clues are easier to piece together. I also don't watch too many movies. I'm mostly talking about just extra long videos not talking about movies.I do watch a lot of gaming retrospectives, though.