If you download and install http://fpdownload.macromedia.com/pub/flashplayer/current/licensing/win/install_flash_player_11_plugin_32bit.exe, does Flash begin to work? IE and Firefox use different Flash plugins, so it is possible the Firefox one isn't properly installed.

Thanks, but that doesn't work either. After clicking on a FaceBook embedded video, it still turns into a blank/black box.

Is the Flash player loaded if you right-click that black box where the player should be?

Does it help if you 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

For other ideas, see:

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

Right clicking on the black box shows the Flash pop up box with version 11.2.202.235.

Disabling hardware acceleration has no effect.

It is playing embedded video on Facebook from AMCTV & YouTube for instance. The video I'm having trouble with seems to be hosted on Facebook's servers. Just video people upload but aren't using YouTube to host it.

As of 6-7-12 @ 7:55am Eastern the video is working. Funny, 15 minutes ago it wasn't! That said, I am now using Firefox 13 but the problem with Facebook video seems to be intermittent and therefore is most likely on their end.

Thanks for letting us know that the problem with Facebook video seems to be intermittent and therefore is most likely on their end. . I marked this question "solved"