You can turn it off in the options. From <a href="https:&#x2F;&#x2F;support.mozilla.org&#x2F;en-US&#x2F;kb&#x2F;enable-drm" rel="nofollow">https:&#x2F;&#x2F;support.mozilla.org&#x2F;en-US&#x2F;kb&#x2F;enable-drm</a><p>Opt out of CDM playback, uninstall CDMs and stop all CDM downloads<p>You have the choice to globally opt out of HTML5 DRM playback. Once you opt out, Firefox will delete any downloaded CDMs from your hard drive, cease all future CDM downloads and disable DRM playback. This affects only DRM-controlled HTML5 audio and video. To opt out of HTML5 DRM playback completely, follow these steps:<p><pre><code>    Click the menu button  and choose Options.
    Click the Content panel.
    Remove the check mark next to Play DRM content.</code></pre>