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.
^ this is why I like Zwift. It's something to look at but you don't need to concentrate on or listen to.