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 or otherwise make changes.

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

You can check for problems with current Flash plugin versions and try these:

• disable a possible RealPlayer Browser Record Plugin extension for Firefox and update the RealPlayer if installed
• disable protected mode in Flash 11.3 and later
• disable hardware acceleration in the Flash plugin

• http://kb.mozillazine.org/Flash#Troubleshooting

I've noticed this as well. Think Google/Youtube introduced some new code. Used to be, with the AdBlock Plus add-on to Firefox, you don't see the ads on YouTube. I think they got wise to this. You can still view videos, with the AdBlock Plus add-on. Simply click a couple seconds into the video, and it starts.

This is assuming of course, your like me and have the AdBlock Plus add-on.

Some more reports today. Did you find a solution that might help?

• Firefox freezes when I go to Youtube videos
• Firefox hangs/crashes whenever viewing youtube videos on youtube

I'm just assuming it's related to AdBlock Plus. If I disable it, videos load fine, but with ads. God forbid YouTube miss out on revenue!

My trick works, leave adblock on, and just click a couple seconds into the video, and it loads. Maybe next Adblock update will fix?

I dont know why this fixed it for me but try this,

1. open YouTube with browser in full screen.

2. open new browser window and shrink about half screen size

play your video in background and have the new 1/2 window in primary focus but over to the side so you can still watch your video while you are surfing,working on the 1/2 sized window.

Could it be something with my extensions? The only ones I have are Troubleshooter 1.0a, Turn Off the Lights 2.1.0.3.0, Wiktionary and Google Translate 6.0, and 1-Click YouTube Video Downloader 2.0.4.

I don't think it has anything to do with extensions, I don't have any that you have listed and my wife doesn't use any that I have but the problem is the same on our different computers, another thing I have noticed is that constantly moving your mouse while watching YouTube keeps the video from freezing also.

Hi Epsilon01, it's easy to check. Just disable the extensions and restart Firefox to test. You can re-enable the ones important to you just as easily.

orange Firefox button (or Tools menu) > Add-ons > Extensions category

The YouTube Video Downloader extension sounds like the most likely candidate.

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

Had the same problem. After flash update to 11.6 firefox started to freeze on any site running flash (including youtube). It helped to switch protected mode off in

C:\Windows\System32\Macromed\Flash\mms.cfg

(Have added ProtectedMode=0 string to the file)

I have 32bit version of Windows 7

I've been having this problem for a while and then it goes away. it always happens after my Flash player is updated. It happens with all browsers, no exception. So today i finally fixed it. Here's what worked for me:

1. - I Googled "uninstall Flash player"which took me to the right uninstall file to download. then I ran it. Then I tried youtube and couldn't see anything which confirmed that Flash was gone.
2. - I temporarily shutoff my Anti-virus.
3. - Dow loaded the latest Flash player
4. - I right clicked the install file, chose Run as Administrator.
5. - The first time nothing happen so I ran again and this time installed the Player.
6. - tested youtube on all browsers, it works like new!!

This worked for me too. I have two monitors so all i did was open a second firefox window, moved it to the other screen, clicked on it to make it the focus and voila, no more freezing

I just removed Video DownloadHelper 4.9.15 add-on and voila, Firefox doesn't freeze anymore. If you have it you better remove it. It worked for me maybe it will work for you!

I think you know how to remove an add-on but if you don't, read below:

• In order to uninstall a possibly unwanted extension, please do the following:

1. From the Firefox window click the Firefox button at the top left and select Add-ons, or, if the Firefox button is not shown, click the Tools menu and click Add-ons.
2. Once the Add-on Manager has opened in a new tab, click the Extensions button on the left side of the window.
3. You should now see a list of your installed extensions on the right side together with buttons on the right side of each extension.
4. To remove an extension from Firefox, simply click the Remove button. You should see a message that informs you about the successful removal of the add-on.
5. Note that some add-ons require a Firefox restart to be removed completely. To perform a Firefox restart after the add-on removal, click the Restart now link in the message.

• You can find further information about uninstalling extensions in the following articles: Disable or remove Add-ons