No matter how engaged in something I am, I cannot just sit there. Around every 20 minutes I have to stand up and start walking around aimlessly (pacing). The closer to an emotional climax in a story I am, the more intense this becomes.
This is annoying to me because sometimes I want to watch something all the way through, but I just cannot. And it's hard to become immersed in another world when I'm constantly walking around the one I'm already in every 20 minutes. Maybe if I'm with other people or in a setting, for example a movie theater, I might be less likely to walk around. But for the most part I do it when I'm alone, and that's when I enjoy most pieces of entertainment.
If I'm playing a video game, these walking breaks usually happen between missions or loading screens, depending on how the game is structured. During movies, this happens either between scenes, or during advertisements. I kind of like the advertisements, not because I like ads, but they're a good point to take a break.
I wish video playing applications, like VLC Media Player for example, had a feature where you could insert fake ads. There probably is a feature somewhat like what I'm describing that I don't know about. The fake ads could just be a random demo video that comes with your computer, or parody. It doesn't really matter, just an indication that it's time to walk.