I've done pretty hard intervals in the past before and never had an issue having the TV on. I wouldn't use something dialogue heavy but Game of Thrones or the Walking Dead is usually pretty okay, even if I'm not exactly hearing everything towards the end of an interval.
Personally I found I either watch/listen to the tv and end up soft pedalling, or I concentrate on putting in effort and barely notice what's on the screen so it could just as well be colourful blobs moving around.
I've done pretty hard intervals in the past before and never had an issue having the TV on. I wouldn't use something dialogue heavy but Game of Thrones or the Walking Dead is usually pretty okay, even if I'm not exactly hearing everything towards the end of an interval.