Sorry but Firefox seems still to have problems with FlashPlayer 11.3 on Windows.

Please for now try uninstalling FlashPlayer 11.3 and downgrading to FlashPlayer 11.2 or 10.3. (Also note there may be a separate issue if used with RealPlayer). Developers from Firefox and Flash have been trying for a few days to get reliable fixes to these issues,

See for instance the latest revision of

• flash 11.3 crashes and any articles linked from that.

Update.

Although not as straightforward as sticking with Flash10.3 a better option now ( Especially as security patches have been released for FlashPlayer. ) may be to use whatever the current version of FlashPlayer is but try with Adobe FlashPlayer's protected mode disabled. Full instructions on how to do that may be found in the article

• http://kb.mozillazine.org/Flash#Flash_Player_11.3_Protected_Mode_-_Windows

You may find that the Mozillazine articles are more up-to-date than official Mozilla Firefox KB articles, are likely to go into finer detail, do not shy away from giving alternative and sometimes more complex solutions

I find that the problem only occurs on my (new) laptop which runs Windows 7. On my (old) Windows XP PC I can watch Flash videos in Firefox without any trouble. I tried uninstalling Flash 11 from the laptop and replacing it with 10, but it made no difference. Flash is fine on the laptop in Chrome and IE9, but I'd rather use Firefox!

This issue does not affect IE or Chrome. And it does not affect Windows XP as that is unable to use protected mode (that is a security enhancement that is proving problematic)

Have a look at the general information in case you have a different problem

• Flash Plugin - Keep it up to date and troubleshoot problems
  • but please bare in mind that until the current issue is fixed 11.3 may not work
  • and with FlashPlayer enabled, use Firefox to visit the test site:
    • http://www.adobe.com/software/flash/about/

if you continue to have problems please start your own thread by asking a question

1. use link [/questions/new]
2. follow the links and prompts that you get
3. when prompted please please follow the instructions that tell you to copy the troubleshooting information.

I uninstalled RealPlayer and bam! Youtube, Yahoo and other vids now play.

Note if you have RealPlayer and want to keep using it there may be workarounds,and RealPlayer developers may well be working on fixes. Other forum posts may offer suggestions, and the KB article has recently been updated:

• Fix problems with RealPlayer add-ons

If you are using Flash 11.3 on Firefox Windows >=Vista, Windows 7 note that there are currently known issues and that some users are finding it necessary to downgrade from FlashPlayer 11.3 as explained previously.
In such circumstances it may be necessary to ignore the advice from the pluginchecker.

<This is not a FlashPlayer issue. It's a 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 !

There are multiple possible problems, if anyone has a problem with YouTube videos and reading the information in this and other threads,or the linked articles does not help please start your own thread by asking a question.

Please note some of these issues may relate to RealPlayer or Flash 11.3 use and relevant developers are working on the problems.

(A new RealPlayer release has been made recently but is or will be blocklisted by Firefox, possibly this time as a Hardblock that will not be easily re-enabled)

Thanks blacksabbath71! This solved my problem. Now I can play videos again.

You're welcome mazberry ! Glad to have helped you. In following my instructions you will still be able to play videos in the Realplayer library if you have any in it using Realplayer as well as play videos from Youtube and other websites while using Firefox .You will not be able to download a Youtube video to your computer since the Youtube download uses the Realplayer Web download which you disabled to resolve the issue you had. 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. If you uninstall Realplayer, you'll resolve the Firefox issue but you'll no longer have Realplayer. My instructions that you followed gives you the best of both worlds.

This worked great for me too. It also allowed my download manager to start working again. THANKS

You're welcome jwm244343 ! Glad to have helped you too.

I upgraded from firefox 8 to 14 and installed the latest version of flash player 11.4 causing ytube video problems. I then uninstalled 11.4 and re-installed 11.3 but the ytube videos still would not play. Finally, I uninstalled 11.3 and installed 10.3. Now all youtube videos are playing smoothly once again.

This solution did wonders for me and restored my faith in firefox. Thanks.

Firefox updated several add-ons today and now I cannot watch a YouTube video from the website or through FEDbook. I'm spent trying to fix this coming from the typewriter generation. Let me know when you all figure out a fix. I'll use Opera in the meantime.

i dont even have realplayer installed on my pc , and all my other browers play flash video fine.

i havnt been able to play youtube videos on firefox for years , it plays everything else but youtube .

jay2thou, If we take the comment

i havnt been able to play youtube videos on firefox for years , it plays everything else but youtube . 

literally, then it appears that you must have a different problem to others in this thread.

If you have had a problem with you tube for a number of years we can rule out that your problem is due to

1. Flash 11.3 or later, / protected mode
2. or due to you enrolling as a html5 beta tester on YouTube.

Maybe you should check you have no security software etc blocking the site, and that you have not set up exceptions to block content, javascript or cookies.
See

• Block and unblock websites with parental controls on Firefox
• Settings for web content, pop-ups, fonts, and languages
• Websites say cookies are blocked - Unblock them