Hi mrm1, YouTube recently discontinued support for Flash, so users of Windows XP and some users of Vista are having problems using the site.

On Windows, Firefox requires the Microsoft Media Foundation in order to decode H.264/MP4 videos. Based on your results on the YouTube test page, you may not have it. The most relevant article for Vista users would be this one, which you might already have seen: Fix video and audio problems on Firefox for Windows N editions. Is that what led you to the Microsoft download you were trying to install?

Two other things:

Extensions

If you use any YouTube specific extensions, try disabling them since they probably have not yet been updated to work with the changes. Same for any video recorders or downloaders. You can do all that on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons
• type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions. Then cast a critical eye over the list on the right side. Any extensions that Firefox installs on its own are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything video or YouTube related? If in doubt, disable.

Often a link will appear above at least one disabled extension to restart Firefox before the change takes effect. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

HTML5 Video Settings

I think it might be helpful to check some settings, as well. Here's how:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste med*ena and pause while the list is filtered (this will match all the true/false preferences in the form media.something.enabled)

(3) If any of the following preferences are bolded and "user set" to false, double-click them to restore the default value of true

• media.mediasource.enabled
• media.mediasource.mp4.enabled
• media.mp4.enabled
• media.ogg.enabled
• media.webm.enabled

Then try the https://www.youtube.com/html5 test page again (if you still have it open, try reloading it using Ctrl+r or clicking the reload arrow in the address bar). Any improvement?

Okay...thank you, JS 2000. I will "try" to resolve this by following your suggestions. At first glance, they are a little unnerving and daunting. Thank you..again.

I am really way out of my comfort zone here...

Apparently, you tube has resolved the issue (and some had said that it was THEIR issue to solve).

As of this morning, I am able to view you tube. I'm relieved - issue resolved! I'm disappointed that firefox didn't address this particular issue directly (or did they) and try and calm their many users' stress levels.

If you read you tube or any site related, this has been problematic for thousands of you tube users in the past year. Why Firefox didn't alert or come out and address it as it was happening and bring a level of reassurance to their users is surprising to me.If they have in and I have missed it, sorry for the bluster.

Hi mrm1, I've only seen reports of problems on Vista in the last 24-48 hours, so I don't know what was going on there. Obviously lots of problems on XP going back over time.

I followed your suggestions re the extensions and it worked. YouTube is working fine for me. There are still outage issues for others but the little that I have used it, it has been fine. Thank you.