You are not alone: someone else reported the problem this afternoon as well: Firefox freezes when I go to Youtube videos. Note: unsolved as of this moment.

Do you have any add-ons related to video, such as downloaders? If so you might try disabling them to see whether that makes any difference. You can do that here:

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

Check both the Plugins and Extensions categories.

Youtube, like other Google sites, is a complex and frequently changing application. When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Bypass Firefox's Cache

Use Ctrl+Shift+r to reload the page fresh from the server.

Alternately, you also can clear Firefox's cache completely using:

orange Firefox button (or Tools menu) > Options > Advanced

On the Network mini-tab > Cached Web Content : "Clear Now"

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site:

• right-click and choose View Page Info > Security > "View Cookies"
• Alt+t (open the classic Tools menu) > Page Info > Security > "View Cookies"

Then try reloading the page. Does that help?

Also, do you usually use YouTube logged in? I generally do not log in, so I'm not sure whether I'm replicating your setup.

If you want to use firefox with youtube then the bad news no version will work smoothly and there are thousands of posts since version 13.01 (the only version that will work with youtube well and with 10.3 flash version specifically) that all of them showing the problems of lack of compatibility between firefox and youtube. So don't waste your time, Adobe has stopped supporting firefox since they teamed up with Google Chrome. Either use firefox 13.01 with flash 10.3 or change your browser to Chrome or internet explorer but you will loose the great features of firefox.

Hi nofal, last Summer was a mess, but the problems were mostly cleared up last Fall. I use YouTube all the time with the latest version of Flash. There are support articles on how to fix the common problems that Flash 11.x had with Vista and Windows 7 due to the introduction of "protected mode" and Real Networks fixed the problem with its recorder/downloader. There is no need to roll back to Flash 10.3 or use other browsers.

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

Like someone said.... Since google bought Youtube... Maybe they even put a test : if firefox... freeze.. in their program...