There are three images here. The first is what I see when I load youtube. The second is what I see when I load a direct link to a video. The third is what I expect to see (this was loaded in Chrome). Please note that this issue occurs on both my home and work computers, which both run Windows 10. I prefer to use firefox but I can't use it for youtube.

Make sure you are not blocking content. [https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Start Firefox in Safe Mode] {web link} by holding down the '''<Shift> ''(Mac=Options)''''' key, and then starting Firefox. A small dialog should appear. Click '''Start In Safe Mode''' (not Refresh). Is the problem still there? ------------------- Many site issues can be caused by corrupt cookies or cache. * Clear the Cache and * Remove Cookies '''Warning ! ! ''' This will log you out of sites you're logged in to. You may also lose any settings for that website. Type '''about:preferences'''<enter> in the address bar. * '''Cookies; ''' Select '''Privacy. ''' Under '''History, ''' select Firefox will '''Use Custom Settings. ''' Press the button on the right side called '''Show Cookies. ''' Use the search bar to look for the site. Note; There may be more than one entry. Remove '''All''' of them. * '''Cache; ''' Select '''Advanced > Network. ''' [v57+] Select '''Privacy. ''' Across from '''Cached Web Content, ''' Press '''Clear Now. ''' If there is still a problem, '''Start Firefox in Safe Mode''' https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode A small dialog should appear. Click '''Start In Safe Mode''' (not Refresh). Did this help? While you are in safe mode; Try disabling graphics hardware acceleration in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches. ''[https://support.mozilla.org/en-US/kb/forum-response-disable-hardware-acceleration How to disable Hardware Acceleration]'' {web link}