Hi  !
You can check to see if your plug-ins are up to date here:
https://www.mozilla.org/en-US/plugincheck/
(that option is no longer in 3-bar menu > Add-ons > Plug-ins,   as Firefox will stop supporting NPAPI plug-ins some time soon)

Ok, but how do I see if the non-npapi plugins are up to date?

soundwave said

Ok, but how do I see if the non-npapi plugins are up to date?

You can check   all   plug-ins there   ! (I should have mentioned that,   sorry   !)

soundwave said

Ok, but how do I see if the non-npapi plugins are up to date?

Firefox doesn't use any Plugins that aren't NPAPI, although many aren't visibly labeled as such.

NPAPI = Netscape Plugin Application Programming Interface Netscape created Mozilla as an open source arm of Netscape Communications Corporation in 1998.

But when I go to https://www.mozilla.org/en-US/plugincheck/ several of my plugins are not shown there. Specifically: Primetime CDM, OpenH264, and Widevine CDM

soundwave said

But when I go to https://www.mozilla.org/en-US/plugincheck/ several of my plugins are not shown there. Specifically: Primetime CDM, OpenH264, and Widevine CDM

The Plugin Check page is just a website, and Firefox does not advertise to websites that you have those three plugins. Firefox should keep them up-to-date, if there are any updates, as part of the related features.

Let's compare: when I open the about:plugins page -- type or paste that internal "address" in the address bar and press Enter/Return to load it -- I get these version numbers:

OpenH264 Video Codec provided by Cisco Systems, Inc.

   Version: 1.6

Primetime Content Decryption Module provided by Adobe Systems, Incorporated

   Version: 17

Widevine Content Decryption Module provided by Google Inc.

   Version: 1.4.8.903

But I don't know how to find out if those are the latest versions...