A friend mentioned that there is a smart box that you can hook up to your TV, that allows for seeing new movies before they come out, anyone know which ones are good for this?
Yes, it's called The Time Machine. It's the only one that will let you see new movies before they come out. It's a very smart box. But unless you have a contact, you won't be able to get one for about 50 years.
Or perhaps you were thinking of something that can access movies before their official release on DVD/Blu-Ray? There are lots of online services that offer that, and lots of ways to access them. But the quality of pre-release movies is pretty variable. Sometimes they can be good quality digital leaks, like the Oscar screeners. More often they would be crappy recordings from a movie theatre screen, or foreign-language releases with bad dubbing and subtitles.