I totally understand the impulse to not just veg out in front of the TV but to want to do something involving movement if you can while the show is on. I think an element of criticism has crept in here in some of the responses and I think it is unwarranted. Some of us just find it hard to sit still and do nothing even while watching TV and this need to fidget needs to be translated into something positive!
Some people take barre classes daily, some instructors instruct it daily and if they do so, they must not be feeling ill-effects. I walk daily, pretty fast, anything from 5 miles and up, and no, I suffer no ill-effects. Only trial and error will tell if you can do barre more frequently and use this as a way of incorporating movement while watching your fave show.
Do you have a treadmill? If so, walking or running are good things to do while the show is on. You might also do some matwork, pilates work, yoga work, stretching work in front of the TV, or use this time to do a series of 100 lunges, 100 squats, 100 deadlifts, etc, etc, whatever works for you. I used to weight train while watching CSI because I went through a period of de-motivation and the only way I could do the weights was if my brain had something else to distract it. As an anxiety and depression sufferer, this strategy helped me a lot: the exercise helped with depression and the distraction of the TV helped lower anxiety and distracted the brain from endless loops of negative thinking. I did this for a whole year, it helped me stay sane and I got very strong actually! Stronger than I am now.....
You see, there are many reasons why someone might choose to do some exercise while also watching TV. I see nothing wrong with it at all. Cathe may be right: if the workout is the top priority, doing it in front of a television show will detract from your abilities to give your workout your full, 100% focus. However, if you still derive benefit from your chosen method of movement while watching a fun show, then I say "go ahead" because movement is good, movement still counts, and no-one can know your reasons for doing what you do and what you need like you can.
Clare