If you are a starter, you may be unfamiliar with the digital copy files. Actually, digital copy movies widespread in our lives. They are special movie types. The following passage is the description of digital copy.
Digital Copy enables buyers of DVD and Blu‑ray to receive the standard definition digital version of the movie in their choice of iTunes or Windows Media formats. Digital Copy is located on a stand-alone disc and is Mac & PC compatible.
As far as i know, except Blu-ray and DVD digital copies. iTunes movies or TV shows, Amazon Instant Video and other media files purchased from online stores. Also are digital copy movies. These media files are protected by DRM protection. So digital copies are incompatible with many devices, only authorized devices can play them smoothly. Though Google Nexus 7 2 tablet is the most powerful 7 inch tablet, it doesn’t have a license to play digital copies.