Did you check for issues caused by an extension that isn't working properly?

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

• Switch to the DEFAULT theme: Firefox/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

See also:

• https://support.mozilla.org/kb/Backing+up+your+information
• https://support.mozilla.org/kb/restore-bookmarks-from-backup-or-move-them

Hi,

thanks for your reply.

My youtube videos perfectly loads in safe mode. However, it does not in the normal mode. So I tried unchecking hardware accelerator, used default theme, and disabled the addons, but the youtube videos still won't load. This situation is very irritating. Is there another way to solve this problem?

Are you using code in userContent.css that might be causing this?

• http://kb.mozillazine.org/userChrome.css
• http://kb.mozillazine.org/Editing_configuration

In Firefox Safe mode these changes are effective:

• all extensions are disabled (about:addons)
• default theme is used (no persona)
• userChrome.css and userContent.css are ignored (chrome folder in profile folder)
• default toolbar layout is used
• JavaScript JIT compilers are disabled
• hardware acceleration is disabled (Options/Preferences > Advanced > General)

• plugins are not affected
• preferences are not affected

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History > Show All History" or "View > Sidebar > History") or via the about:permissions page.

Using "Forget About This Site" will remove all data stored in Firefox from that domain like bookmarks, cookies, passwords, cache, history, and exceptions, so be cautious and if you have a password or other data from that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of the involved files.

It doesn't have any lasting effect, so if you revisit such a 'forgotten' website then data from that website will be saved once again.

I reinstalled Firefox and the problem was solved. I have to say I am pretty disappointed with the support that I have got here. The helpers listed all the ways that I try to fix the problem but none of them worked. Also backing up data did not do anything. I lost all my history and saved password even though I followed the exact same steps as you gave me.

Seems like a lot of people are facing the youtube video problem, hope you guys can figure out how to fix it so that everyone is satisfied with using your service.

Thank you.

junlee_23

Why reinstall? You would try refresh...

https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings

Look on your desktop. Do you see a folder called; Old Firefox?

https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

These can't get your data back, but will help in the future.

These add-ons can be a great help by backing up and restoring Firefox

FEBE (Firefox Environment Backup Extension) {web link} FEBE allows you to quickly and easily backup your Firefox extensions, history, passwords, and more. In fact, it goes beyond just backing up -- It will actually rebuild your saved files individually into installable .xpi files. It will also make backup of files that you choose.

OPIE {web link} Import/Export extension preferences