I can see TV shows that I previously purchased in my iTunes library, but when I go to play them, it appears I have to buy them and I can only see a short snippet of about 30 seconds or so. How can I get access to episodes I previously bought?

When I look in my iTunes library under “Purchases,” I see episodes of TV shows that I previously bought. However, when I try to play them there is a cost next to them, as if I need to buy them again to watch. When I go to play, I can only see a short snippet that is about 30 seconds long. Shouldn’t I be able to access them on different devices (especially since I no longer own the devices I originally purchased the TV shows on)?