What is usenet and how do I get it

Usenet is a very very old part of the internet that predates the WWW. It was originally developed as a discussion group type of thing. Basically a precursor to message boards. It is still used as such, but I think what you are after is using it to get movies and tv shows. Because of how old it is and it's original intent, it is a little more complicated than simply downloading a movie file. Lifehacker has a decent guide here: LINK

Giganews is really expensive for what it is, I would recommend Supernews which is basically a giganews reseller for a third of the price.

I have a gigabit fiber connection that I can easily max out using usenet.

The first rule of usenet is you don't talk about usenet