Your System Details shows;

Installed Plug-ins

Shockwave Flash 22.0 r0 Shockwave Flash 11.6 r602
Having more than one version of a program may cause issues. You must remove the older programs. Then get the current full installer.

Flash: Grab the uninstaller from here: Uninstall Flash Player | Windows Uninstall Flash Player | Mac

Then reinstall the latest version.

Note: Windows users should download the active_x for Internet Explorer. and the plugin for Plugin-based browsers (like Firefox).

Note: Windows 8 and Windows 10 have built-in flash players and Adobe will cause a conflict. Install the plugin only. Not the active_x.

Flash Player Version: 22.0.0.209 Flash Player (Linux) Version 11.2.202.632

https://get.adobe.com/flashplayer/ Direct link scans current system and browser Note: Other software is offered in the download.

https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, Win IE . . . .) Note: Other software is offered in the download.

See if there are updates for your graphics drivers https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration

hi efroim, have you set browser to update automatically in the firefox menu ≡ > options > advanced > update panel and what security software are you using on your system?

If you already have Firefox set to update automatically, then the problem could be that your security software is intercepting the HTTPS request to download the needed components from Mozilla's servers, as reported here:

Bug 1300633 - Users report Netflix stopped working after Firefox 48 as CDM won't get installed _{See Bugzilla etiquette before commenting in bug reports.}

Please tell us What security software are you using. You could try to disable the interception of secure connections in your security software settings, as explained in the "Antivirus products" section this article: How to troubleshoot security error codes on secure websites