Untill now, Firefox browser comes with the plugins Wildwine Content Decryption module, Adobe Primtetime CDM (including OpenH264 Video Codec) in activated or enabled state by default, these plugins will be downloaded and installed shortly after running browser for the first time. This allows users to view DRM content right away.
This to change from Firefox 52 onwards, the browser maker has decided to disable Primetime CDM plugin, so that it won’t be downloaded and installed until and unless user visits a site with DRM content that needs plugin to be enabled, then Firefox prompts to user to turn on DRM, when user clicks on ‘Enable DRM’, browser will download and install Primetime CDM plugin components in the background.
Firefox no longer downloads Adobe Primetime CDM by default from version 52
Meanwhile, if you visit the plugins panel, you’ll notice the plugin being installed, with the message highlighting ‘Primetime content Decryption module Provided by Adobe Systems, incorporated will be installed shortly’.