To see how well your Firefox handles different media formats, could you use this test page and see whether you have any red boxes:

https://www.youtube.com/html5

jscher2000 said

To see how well your Firefox handles different media formats, could you use this test page and see whether you have any red boxes: https://www.youtube.com/html5

No red boxes, all blue with checks.

Hi   !

Just a shot in the dark,   but, have you checked if there are updates for your graphic drivers  ?   See this article:
'Upgrade your graphic drivers to use hardware acceleration and WebGL':
http://mzl.la/1xKsEca

If you are using a private window, could you check for a shield icon at the left end of the address bar? That indicates Tracking Protection is blocking something in the page. For more information, see: What happened to Tracking Protection?.

You might also try making a exception in Adblock Plus so that no ads are blocked on the page in case that is causing an issue.

Happy112 said

Hi   !
Just a shot in the dark,   but, have you checked if there are updates for your graphic drivers  ?   See this article:
'Upgrade your graphic drivers to use hardware acceleration and WebGL':
http://mzl.la/1xKsEca

The graphic drivers are up-to-date.

jscher2000 said

If you are using a private window, could you check for a shield icon at the left end of the address bar? That indicates Tracking Protection is blocking something in the page. For more information, see: What happened to Tracking Protection?. You might also try making a exception in Adblock Plus so that no ads are blocked on the page in case that is causing an issue.

I've tried this too with GP on chat, there is no shield icon in my bar when using private windows.

Let me say, videos on GP play fine, except for this one movie. This movie plays fine in Chrome too, just won't play in Firefox.

dgrubbs7984 said

Let me say, videos on GP play fine, except for this one movie. This movie plays fine in Chrome too, just won't play in Firefox.

Unless you see a specific error message in the console, I don't think we'll have any more guesses. You can try this:

• Open the Browser Console using either
  • Ctrl+Shift+j
  • menu button > Developer > Browser Console

• Click the trash can at the left end of the button bar in the console to clear previous messages

• Reload the page of the nonplaying video and then check the new messages in the console -- you can ignore the blue triangles, those style rule warnings are not likely to be relevant -- you can copy/paste any that sounds like they could be an issue

Okay, I opened the link straight for the video, cleared all the messages then clicked watch, and got the error in the developer window:

It was a long YouTube link (which is the video I would assume? "was blocked due to MIME type mismatch (X-Content-Type-Options: nosniff)."

then this error - "Error: Permission denied to access property "href""

This site appears to use a scroll-linked positioning effect. This may not work well with asynchronous panning; see https://developer.mozilla.org/docs/Mozilla/Performance/ScrollLinkedEffects for further details and to join the discussion on related tools and features! movies

The resource from “https://s.youtube.com/api/stats/qoe?event=streamingstats&cpn=Bx2QzM2ZUGr5_6u9&ei=TVflV4ibHdiQuwLn0aXQCQ&el=embedded&docid=efBgXjbd2uQ&ns=gp&fexp=9422596%2C9428398%2C9431012%2C9433096%2C9433221%2C9433946%2C9434047%2C9434289%2C9435526%2C9436964%2C9439580%2C9444161%2C9444637%2C9446054%2C9448261&cl=133923007&html5=1&c=WEB&cver=1.20160922&cplayer=UNIPLAYER&cbr=Firefox&cbrver=50.0&cos=Windows&cosver=10.0&vps=0.000:N,0.019:B,0.256:ER&cmt=0.019:0.000,0.256:0.000,0.256:0&error=0.256:fmt.noneavailable:0.000:nosupported.1&bh=0.256:0.000&bat=0.256:1:1&vis=0.256:0” was blocked due to MIME type mismatch (X-Content-Type-Options: nosniff).(unknown)

Error: Permission denied to access property "href"

Out of context, that particular address sends me a blank page (content-type HTML), so if it's supposed to retrieve the video, something is definitely wrong or there's just no way to test it without paying for it. Which isn't high on my list... perhaps you should delete it in case it reflects negatively on your account somehow to have random strangers clicking it.