Digital rights management (DRM) is a set of access control technologies for restricting the use of proprietary hardware and copyrighted works. DRM technologies try to control the use, modification, and distribution of copyrighted works (such as software and multimedia content), as well as systems within devices that enforce these policies. Many internet music stores employ DRM to restrict usage of music purchased and downloaded. This technology may restrict some of the things you can do in the browser. While some DRM-controlled content can be viewed using the adobe flash plugin, many services are moving towards HTML5 video that requires a different DRM mechanism called a Content Decryption Module (CDM).
DRM in Chromium using widevine
DRM media can be viewed in Chromium using Google's chromium-widevine plugin.
DRM in Firefox using flash
DRM media can be viewed in Firefox using the adobe-flash-plugin