When in iTunes under TV shows, press the show to view it for free, rather than downloading it. Tell me if it works for you too!
I doubt it's a glitch, you just have to buy it to watch it offline. But wait, isn't it just usually a preview, not the whole show?
Huh? You mean like streaming a TV show you already have? Or do you not have to purchase it at all and watch it for free?
I doubt Apple is this stupid, and anyways, google enough and you can find nearly any TV show or movie for free.