I always get a black screen & error message with YouTube, white screen on Facebook videos.

If you use extensions (Tools > Add-ons > Extensions) like Adblock Plus or NoScript or Flash Block that can block content then make sure that such extensions aren't blocking content.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do not click the Reset button on the Safe mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

You can check for problems caused by Flash updates and try these:

• disable a possible RealPlayer Browser Record Plugin extension for Firefox and update the RealPlayer if installed
• disable protected mode in Flash 11.3 and later
• disable hardware acceleration in the Flash plugin

• http://kb.mozillazine.org/Flash#Troubleshooting

Once I got to Safe Mode, I couldn't find anything where I could do Tools.

I am a historian, not a tech. I should not have to be a tech to make Firefox work the way it has worked satisfactorily for years. Firefox should not be improving my experience so that I can't work with it.

Since before Christmas, I get NO videos anywhere, and am mostly unable to look at slide shows, except for NatGeo & NYTimes.

Did any video work on those websites when you started Firefox in safe mode?

First check if you have the Flash plugin installed and enabled in Firefox/Tools > Add-ons > Plugins.

• http://www.adobe.com/software/flash/about/
• http://helpx.adobe.com/flash-player.html