Best thing you can do with your Roku is to put a program called Kodi (Xbmc) on it. Then get video add-ons. One in particular called 1channel it has about 60,000 movies and tv shows for free. There are tons more video add ons. Just google how to add kodi to the Roku it's quite simple.
I run kodi on my Mac and mirror the screen from the Mac to my Apple TV.