Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

• Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"

"Remove Cookies" from sites causing problems:

• Tools > Options > Privacy > Cookies: "Show Cookies"

Start Firefox in Use Troubleshoot Mode in Firefox to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode

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

I have tried all those things, and I still have the problem.

Try to "Disable the hardware acceleration" in the Flash Player.

• http://helpx.adobe.com/flash-player/kb/video-playback-issues.html

See also:

• https://support.mozilla.org/kb/Cannot+view+full+screen+Flash+videos

Flash "Display settings" window:

• http://www.macromedia.com/support/documentation/en/flashplayer/help/help01.html

This still did not work. I have noticed that FireFox will not play any video on any website. I am able to play all video using IE browser.

is the flash plugin even listed in firefox > addons > plugins?

What does the Adobe test page say?

• http://www.adobe.com/software/flash/about/

You can find the latest Flash player for Firefox on this page.

• http://www.adobe.com/special/products/flashplayer/fp_distribution3.html

For Firefox on 64 bit Windows, you need the 32 bit Flash version version for a 32 bit Firefox version..

Yes it is

On the Flash player support page, after I re-installed the flash player, the support page was able to identify that it was installed correctly. I try to view a video, but I still can't play video. I close FireFox browser. I open the browser again and go the same flash player support page (http://helpx.adobe.com/flash-player.html) and it no longer detects the flash player installed. I don't see the "F" icon or get any error message. It still appears in the FireFox add-ons though.

Every new version comes plenty of incompatibilities, try to remove firefox and use Chrome!

Hey all, I figured it out finally! I had the same issue, I could not get any youtube videos to load. When I followed the above directions, I could not even get a picture to load to see if I had Flash loaded. I reinstalled, still the same issue. This all happened after the last upgrade which somehow managed to install itself all by itself - I had thought I had not allowed it to just automatically install.

But anyway, after hours and hours of searching, I found this page. It is caused by Real Player being allowed to download videos on IE and Chrome. Mozilla is no longer on that list. (doesn't support it)

Click on the Real Player logo on the upper corner of Real Player, click on preferences, click on download and recording, uncheck the box that says Enable web download and recording. Close Real Player and close Mozilla, restart Mozilla and your issue should be resolved.

Here is the page I got it from https://support.mozilla.org/en-US/kb/flash-113-doesnt-load-video-firefox?...

Thanks a lot. Just this solved my problems too.