Just portait videos? Or all facebook videos? What do you mean specifically by "can't play?" It's stuck on loading, refuses to load, returns an error? You might try launching in safe mode in about:support.

It just seems to be videos that were taken in portrait mode on a cell phone and posted on Facebook.

Here is one I can't play: https://www.facebook.com/News13/videos/2723972567822052/ When I click on play it just gets blurred. The progress bar moves across a little then stops.

I have also posted videos from my own cell phone in both modes. If I take them in landscape mode they play fine but in portrait mode they don't.

Again, I can play either format using the Chrome browser. It only happens when using Firefox on Facebook. I'm pretty sure I have watched some portrait videos on You Tube without issue.

I don't know what it would prove or solve if they work in safe mode. I haven't tried that but it would seem to be no less trouble just to change browsers.

The video works for me.

Do you see the controls bar if you hover the player ?

If that is the case then try a different (lower) resolution via the cogwheel (Settings) button to see if that has effect.

It was set to auto. I tried it at 720, 480, and 360. None made any difference.

This video looks fine for me with the correct resolution and dimensions.

If you see blurry content then it is possible that the player's content is excessively zoomed

To answer the question, safe mode launches with no extensions and other things. It's meant to try and isolate the problem to try and see if it's possibly an extension causing the weird behaviour.

Okay tried in safe mode. The only difference is instead of the video screen looking blurred it just turned black. The progress bar advances a little and stops in either case but the video never begins to play.

Again, I can watch videos with Firefox on YouTube that were clearly taken with a cell phone in portrait mode. I can watch this same video on Facebook with the Chrome browser.

It is some combination of Facebook, Firefox, and portrait mode that is causing my issue. Any other format plays fine on the browser in Facebook or other medium.

I guess I was assuming I wasn't the only one experiencing the problem and someone might have an answer if not a fix.

You can check the Web Console for messages about playing media.

• "3-bar" menu button or Tools -> Web Developer
• https://developer.mozilla.org/en-US/Tools/Web_Console

cor-el, I don't see any messages. Clicked around in the Web Console on the debugger and all the other tabs and didn't see anything telling me what is going on.

I don't know that it matters but I failed to mention my operating system or specs. I am running Windows 7 Pro 32 bit. My monitor is a 32" 1080P TV set at 1920x1080 Computer is an old Dell Optiplex 380 I am running Ad Block Plus and Duck Duck Go. Both of these were turned off in safe mode so that shouldn't be the problem.

This issue doesn't come up that often but it's an irritation when it does. My options are to copy the video URL and play it in Chrome or just ignore it. ORR I can just get over it and change browsers.

BTW the video plays okay on my system with Opera also.