I would recommend you to go to Firefox download page and refresh your browser. This must solve your problem. Let me know if it works. Make sure that you are logged in to your Mozilla account. Try the link below. https://www.mozilla.org/en-US/firefox/new/

Hi Cbella, YouTube generally serves MP4-format video using an HTML5 player, that's a player which doesn't use a plugin (for example, it doesn't use the Flash plugin).

Now, I'm basing that statement on Windows, so Mac may vary.

Could you do two tests for me?

Test #1:

To check what player you're seeing (which isn't working), try right-clicking or Ctrl+clicking on the YouTube player and check the "context menu" which comes up. If it's Flash, there will be a short menu referring to Flash on the last line. If you don't see that, if you get a regular Firefox menu, it's probably the HTML5 player.

Which player are you getting?

Test #2:

If you open the following test page, which videos play?

http://www.quirksmode.org/html5/tests/video.html

• Does the "H.264/MP4" video play?
• Does the "WebM" video play?

Thanks.

Also, could you check whether your Flash plugin is up-to-date? You can use the Mozilla Plugin Check site for that (please ignore any other plugins the page wants you to update for the time being to avoid making the situation more complicated):

https://www.mozilla.org/plugincheck/

Hi jscher2000,

Thank you for your time and answer. I just solved the problem by making an update on Adobe Flash.

Best Regards.

Hi Saurabh,

Thank you for your time and answer. I just solved the problem by making an update on Adobe Flash.

Best Regards.