You can check for problems caused by a recent Flash 11.3 update and possibly downgrade to Flash 11.2 or 10.3. *https://support.mozilla.org/kb/flash-113-doesnt-load-video-firefox *https://support.mozilla.org/kb/flash-113-crashes *http://blogs.adobe.com/asset/2012/06/inside-flash-player-protected-mode-for-firefox.html ---- Try to disable hardware acceleration in Firefox. *Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available" *https://hacks.mozilla.org/2010/09/hardware-acceleration/ *https://support.mozilla.org/kb/how-do-i-upgrade-my-graphics-drivers ---- Try to "disable the hardware acceleration" in the Flash Player. *http://helpx.adobe.com/flash-player/kb/video-playback-issues.html See also: *https://support.mozilla.org/kb/keep-flash-up-to-date-and-troubleshoot-problems Flash "Display settings" window: *http://www.macromedia.com/support/documentation/en/flashplayer/help/help01.html

That certinly worked for me. It seems that the problem lies with #Real Player, when I got You Tube videos playing again, all my .flv videos on my PC would not play. I chose another programme to open them with and now everything is fine.

I think it is totally ridiculous. I shouldn't have to jump through all kind of hoops to use FireFox. FireFox needs to jump through all the hoops first and fix their problems. Let me know when you get it all fixed. In the meantime...I'll just go back to using IE. At least it works!