Do you see the Flash plugin on the Tools > Add-ons > Plugins and the about:plugins page?

Does the Flash test site confirm that the Flash player is installed?

• http://www.adobe.com/software/flash/about/

• https://support.mozilla.com/kb/Managing+the+Flash+plugin

The same here. No video on youtube at all, suddenly. I have latest flash player installed.

Download CCleaner, scan and clean....then problem will be solved ;) I fixed mine that way.

The latest Adobe Flash plugin adds a 64-bit player as well as the standard 32-bit player. Youtube seems to set a cookie that conflicts with the 64-bit version and therefore causes you to see a black screen when trying to play videos. The following steps should fix your issue if it is related to this update:

1. Click the Firefox menu on the top left (or the Tools menu if you use the menu bar).
2. Go to History -> Clear Recent History (Omit first part from the Tools menu).
3. Make sure both Cookies and Cache are check-marked (feel free to uncheck everything else)
4. Set the Time range to clear drop-down box to Everything.
5. Click the Clear Now button.

You should now be able to play Youtube (and presumably) other videos again. Doing this worked for me anyway...

Hi, please check out this:

https://support.mozilla.com/en-US/questions/897480#answer-276602

This did not resolve the problem for me. Sadly. Videos play OK one IE but I don't use it as a rule.

This is a Flash player issue - I uninstalled the latest Flash Player and reinstalled Flash 10.3 and everything seems to be working again.

(Youtube videos were just coming up as a black box with a play button - when I pressed this I got the message "An error has occurred - please try later"