You buy the Roku box (there are different kinds and price ranges). We bought the $70 version. You simply plug it into your tv and login to your wifi. On the Roku website you choose the channels you want - some are free (like BYUtv, NBC news highlights, and the Mormon Channel) and some cost extra (like Netflix or Hulu). Then you just watch the Roku channel you want right on your tv - the Roku comes with a remote that works just like a normal tv remote.

The BYUtv Roku channel is HD and it has a built in DVR so I can watch games I may have missed. It also gives direct access to an archive of numerous BYUtv shows and past games.

We also use Netflix through it (subscribed to separately). From time to time we use the Amazon Prime channel to watch recent movies (~$4) and they just added a YouTube channel, so now, as a family, we waste time watching things like Star Wars trailers and Minecraft fan videos on our tv - it's fun to do that with my kids.

So, instead of paying $70 a month for cable, we paid one $70 up-front fee and now we choose what we watch and pay for on a pay-per-view basis and I get BYUtv in HD. To be fair, we don't watch a lot of modern tv shows, so I don't know what kind of access people have to some of those, but the few we do watch are usually available through the Hulu channel.