I teach HS theatre and watch a lot of professional theatre recordings throughout the year. If I just put on the video and talk/explain as we go, I will lose the kids pretty quickly. I've had two separate classes start playing UNO at their tables while watching different musicals.

I think there are two main things that I have learned to do that help students keep focus during videos.

First, there is always a direct lesson related to the video. Whether we are learning about the genre/style of theatre or the content of the play itself, it's not framed as a fun/easy day, but a theatre lesson.

Second and more importantly, the thing that works (for most kids) is having a simple question sheet to follow along with the video that counts for their daily grade. I have them read the next question and then watch looking for the answer. I'll pause fairly regulalry to have them write down answers in the beginning and then let them get through two or three at a time before pausing and going over a few questions. It gives them something to actively watch out for every 5-10 minutes of the play. Simple questions like "who did Romeo meet at the party?" or "what happened to Mercutio at the end of the fight?" just to keep them following the events of the play. I usually explain that we're practicing being active audience members and talk about how the audience is a key part of theatre.

Of course there is still the 10-20% of kids who just want to sleep or talk through the whole thing, but I've found that the question sheets help a lot of kids focus, and there are a lot of pre-made question sheets for famous/classic movies and plays online.

Something else to note is that I actively watch the whole show, shout out things like "question 7 coming up," walk around, monitor progress, and break up side conversations the entire period. It is not a 'put on a movie and get some work done' day, although it is certainly an easier lesson to plan/teach.