Hello, Just in case resetting firefox doesn't work here is the link to Firefox 27 ^{Moderator edit: Removed link to Firefox 27 beta. Please use the [[Install an older version of Firefox]] link and if you link to an old version, don't link to a beta/other pre-release or to an old version of a beta. ~m} The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. <br> '''Note''': ''This will cause you to lose any Extensions and some Preferences.'' *Open websites will not be saved in Firefox versions lower than 25. To Reset Firefox do the following: '''For Firefox versions previous to 29.0:''' #Go to Firefox > Help > Troubleshooting Information. #Click the "Reset Firefox"[[Image:Button reset]] button. #Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish. #Firefox will open with all factory defaults applied. '''For Firefox 29.0 and above:''' #Click the menu button [[Image:New Fx Menu]], click help [[Image:Help-29]] and select ''Troubleshooting Information''. Now, a new tab containing your troubleshooting information should open. #At the top right corner of the page, you should see a button that says "Reset Firefox"[[Image:Button reset]]. Click on it. #Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish. #Firefox will open with all factory defaults applied. Further information can be found in the [[Reset Firefox – easily fix most problems]] article. Did this fix your problems? Please report back to us! Thank you.

I did not do anything and it starting working again. Appears to be a YouTube problem that comes and goes.