Probably check that you have javascript enabled and Flash enabled (Tools > Addons > Plugins). Your Flash also seems to be about of date, please try http://www.mozilla.com/en-US/plugincheck/

If that fails please reply with an explanation of what you see when you try to play a video.

Thank you very much. Updating Flash appears to have solved the problem.

I spoke too soon. I seem to be getting a black box where the youtube video should be with no "play" button.

Does Flash does not work properly or will not update help?

Does the issue take place in safe mode?

Flash seems to work. I go to youtube and I can see flash ads but can watch videos. The bizarre thing is I updated Flash as a different computer user (Admin). Everything works fine as that user but when I log back in as myself, I get the issues I'm describing. I've tried rebooting but nothing.

Try to follow those steps without logging in as Administrator:

1. In Firefox, go to the Flash Player download page at Adobe.com and download the Flash installer.
2. At the top of the Firefox window on the menu bar, click the File menu and select Quit.
3. Open the file you downloaded (i.e. install_flash_player.exe), then follow the installer's instructions.

Does that work?

Good lord, that did it. I didn't even have to reinstall Flash. It seems the act of actually exiting via the File menu rather than exiting via the red X at the upper right hand corner reset Firefox to accept the changes.

Thanks so much for taking the time to help with this problem.

eyetalianmouse,

I'm happy the issue was resolved. Please close this thread so that it has a 'solution chosen by...' line at the top and use new threads to ask about any further issues you have. We'll happy to be of help...

Thanks!