Figured out the add on part. FF disabled them until I updated. That problem is solved. Still having the crash problem during vids.

Hmm, I don't know why FB isn't laying out correctly. Sometimes Firefox will mix in obsolete/mismatched files from cache. If you haven't already, could you try clearing Firefox's Web Content Cache. Here's how:

To dump your cache, see: How to clear the Firefox cache (only select "Temporary cached files and pages", don't clear other kinds of data)

If you have a large hard drive, this might take a few minutes.

Testing in Firefox's Troubleshoot Mode: In this mode, Firefox temporarily deactivates extensions, hardware acceleration, any userChrome.css/userContent.css files, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is running:

You can restart Firefox in Troubleshoot Mode using either:

• "3-bar" menu button > Help > Troubleshoot Mode... (before Fx88: Restart with Add-ons Disabled)
• (menu bar) Help menu > Troubleshoot Mode... (before Fx88: Restart with Add-ons Disabled)

and OK the restart. A small dialog should appear. Click the Open button (before Fx88: "Start in Safe Mode" button).

If Firefox is not running:

Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.) A small dialog should appear. Click the Open button (before Fx88: "Start in Safe Mode" button).

Note: Don't use the Refresh without first reviewing this article to understand what will be deleted: Refresh Firefox - reset add-ons and settings.

Any improvement?

Also, Add ons are mysteriously disabled. I removed the adblockers, and tried to relaod them The downloads failed. My remaining add ons are disabled I am not able to enable them.

About the add-on part, you may want to see the following article Update Firefox to prevent add-ons issues from root certificate expiration.

tl;dr A root certificate in old Firefox versions on desktop and Android version < 128 expired on March 14.