It's annoying when you download an Apple TV app for your favorite entertainment provider only to realize that you cannot access the service due to regional restrictions, the need to connect with your cable service or pay for the service.
Of all the third-party content provider apps available for download in the tvOS App Store, only a handful of services are available on a worldwide basis.
To save you some time, Apple has put together a handy support document which lists all the content providers available on the second, third and fourth-generation Apple TV.