If you want to watch right away, Netflix is testing the 4K streaming waters with select shows (House of Cards, Breaking Bad, The Blacklist) and films (Ghostbusters, The Smurfs 2) if you own a Samsung, Sony or LG 4K TV and have a 25Mbps internet connection.
A PRN file is a special type of file which contains instructions for a printer, it tells the printer what to print on the page and where as well as which paper tray to use, what the paper size is and a number of other controls.
Raw print files, commonly with an extension of .prn or .ps have a number of different uses, the main one being that you can print from an application while you don't have access to a printer and later on print using just the captured file. There is a little more information on the different types of print files here.