The DVD can be a movie, or educational stuff (For example, a documentary about Ireland).
I do this to learn English and also to help me to fall asleep. It is a way to help my brain change focus. Otherwise I would think about my stuff.
I did watch a lot of TV drama series in the past, most of them Chinese. Then I realized that once I started, I would not be able to stop at a reasonable time. Since I did not have much self-control, I stopped doing that.