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

Try this: <This is not a FlashPlayer issue. It's a possible RealPlayer Plugin issue> Follow these steps if you get this message on Youtube "an error has occured-please try again later" and John99's solution doesn't work for you : 1) Disable all RealPlayer Plugins or Extensions on FireFox then close Firefox. 2) Launch RealPlayer and click on the RealPlayer icon at the top left. 3) Click Preferences 4) In the Category panel click Download and Recording. 5) Uncheck (remove check mark) from Web Download and Recording and click OK. NOTE: By disabling this you will not be able to download the Youtube video to your computer since the download uses the Realplayer Web download. You can use free software (FREE YOUTUBE DOWNLOAD) by DVDVideoSoft Free Studio at "www.dvdvideosoft.com" to download a Youtube video to your computer if desired. The video will be downloaded into your Video Libraries folder. 6) Start Firefox and try to play the Youtube videos.

This worked for me. I hope it works for you !

Thank you so much!! I uninstalled Real Player and it worked right away! Thank you thank you!!! :)

You're very welcome ebeh ! If you uninstalled it that's great. If you still wanted to use Realplayer, my instructions would let you. The only thing is you wouldn't be able to download videos to your computer. It would however let you play them on Youtube and other websites. My instructions also tell you to download the DVDVIDEOSOFT Free Youtube download if you wanted to download the video to your computer to play them over and over. This software is real easy to use. If your happy without RealPlayer than all is well.

I have linux with firefox 14.0 and flash 11.2 can't play videos either but all java works.

None of those fixes helped. It's something wrong with Firefox, not Flash, not RealPlayer, etc. I can't play any videos in You Tube or on Facebook, and I can't listen to any music on iHeartRadio or on Rhapsody if I'm using Firefox. However, ALL of these work just fine in Chrome or IE. I've tried reverting my Flash to a lower version, and that works for a day until it auto-updates. I've reset my preferences to disable auto-updating, but it still only works for one day. I've been having these problems for over a month now, and I'm beyond angry. If Firefox doesn't RESOLVE this issue permanently ASAP, then I'll be uninstalling it from my computer and from my kids' computers, and we'll use a different browser.

yeah these fixes are not working, i only got firefox because the live stream i was watching was lagging on crome. firefox cannot even play videos or music. ive tried downgrading flash and i uninstalled realplayer, however im uninstalling this browser.

Hi Vylon, bye Vylon, we hardly knew ya.

What version of Flash do you have? There were some compatibility issues between recent versions of Flash player and some Firefox add-ons or settings. Could you see whether anything in this article helps: Flash 11.3 doesn't load video in Firefox.

You might also consider disabling the new protected mode in Flash 11.3+, unique to Firefox on Windows Vista/7, since that feature is currently being debugged. See this support article from Adobe under the heading "Last Resort": Adobe Forums: How do I troubleshoot Flash Player's protected mode for Firefox?

I had a similar problem. I tried everything. Several tips found in these forums. Solutions found:

Firefox, Tools; Plugins; top of screen "Check to see if your plugins are up to date" update each one.

http://www.mozilla.org/en-US/plugincheck/ Click Update to update a plugin. Complete all recommended updates before restarting your browser.