Hello,

Try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:

• Click the menu button , click Help and select Restart with Add-ons Disabled.

If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

When the Firefox Safe Mode window appears, select "Start in Safe Mode".

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help others with the same problem.

Thanks for your suggestion. Sorry, I should have said. I tried Safe Mode; the problem was the same, and I also refreshed Firefox. Since then, though, I've found that some videos play so am wondering if it's some kind of facebook/Firefox linked issue with some of the video clips.

Please report the videos with problems at https://facebook.com/help

Thank you. I have done.

I have exactly the same problem. Some facebook videos have sound, others not (the majority). It's kinda annoying, and I have tried everything. As you said, no problems on Chrome.

I'm glad I'm not the only one so to that extent your reply is reassuring. I'm at a loss now. I so prefer Firefox to Chrome but it's so aggravating, isn't it, when you go to play something and it's like a silent movie? I'll press on with trying to find a solution

try reinstalling firefox with latest version and use adobe flash player as plug in

Thanks for all suggestions. I'm now stumped. I've uninstalled and reinstalled Flash player. I've uninstalled and reinstalled Firefox. I've followed most of the steps in a 10 point guide; clearing all caches and temp files in case there was a corruption. It seems to be a very random problem; some clips playing and others not from the same person, for instance.

i have the same problem , safe mode , new profile , hardware acc on , of

¡Hola!

Do things improve if you fully remove Adobe Flash as detailed at http://occupyflash.org/#resources ?

Please leave it uninstalled for a while and report back if videos work.

¡Gracias!

What media player is used? Is a Shockwave Flash based player used or the HTML5 media player?

You can check this via the right-click context menu of the player area. A Flash based player shows a context menu with the Flash version.

alex_mayorga said

¡Hola! Do things improve if you fully remove Adobe Flash as detailed at http://occupyflash.org/#resources ? Please leave it uninstalled for a while and report back if videos work. ¡Gracias!

I have done it, and the issue is still here. No sound on facebook videos (although some videos plays sound, it's weird). And of course, as I have said, Chrome has no problems.

Could you please tag https://www.facebook.com/alex.mayorga in one of the problematic videos?

done , send pm to u

Bastinazus: I tried that; still not working properly.

Cor-el: It was Flash Video Player. When trying to suss all this out I realised that there was the option to change to HTML5 so I tried that. Then I got the Youtube Video Player add-on to see if that would make a difference. None of them did

I think it's Firefox-side problem. How can we report this bug to Firefox?

I've just reported it on 'Submit Feedback' from the Help drop down list. There was a Video survey which popped up when I submitted it so I completed that as well.

Try to clear the Flash local storage and settings.

• Windows Control Panel > Flash Player > Storage: Local Storage Settings
  • Remove a specific domain: Local Storage Settings by site
  • Remove all domains: Delete All and Delete Data

Flash Website Storage Settings panel:

• http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager07.html

Global Storage Settings Panel:

• http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager03.html

Flash Local storage settings Help:

• http://www.macromedia.com/support/documentation/en/flashplayer/help/help02.html

Clear the cache and remove cookies only from websites that cause problems.

"Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

Start Firefox in Safe Mode to check if one of the extensions (Firefox menu button/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox menu button/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

all done , even new profile , uninstall flash https://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows.html

same problem , some video play with sound , other dont also i don't have flash right now so i think facebook switch to html5 player

As I have said, i'm pretty sure this is a Firefox-side issue. It has nothing to do with the user.