At the moment, the beta test will be made available only to owners of the Galaxy S2 smartphone for AT&T, where the Media Hub will come with just a limited selection of movies and TV programming for you to purchase for starters. All content is viewable over the smartphone itself, or if you think that your eyes deserve far better (or want to watch a particular movie with family members), then you can always share your content with a 2011-model Samsung Smart TV.
No idea on how far the $25 voucher that intends to get you started on the Media Hub store will bring you, but surely it is good for at least a couple of movies, no?