You can try to delete the YouTube cookies.

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

You need a Firefox version that has MSE (Media Source Extensions) enabled to get this offered.

• http://www.youtube.com/html5/
• http://googlesystem.blogspot.com/2013/10/youtube-shows-if-your-browser-supports.html

• https://developer.mozilla.org/en-US/docs/Web/HTML/DASH_Adaptive_Streaming_for_HTML_5_Video

You can look at the current beta release that comes with media.mediasource.youtubeonly = true.

• https://www.mozilla.org/en-US/firefox/beta/
• https://www.mozilla.org/en-US/firefox/beta/all/

Do a custom install and create a new profile for the Beta release.

• http://kb.mozillazine.org/Creating_a_new_Firefox_profile_on_Windows
• http://kb.mozillazine.org/Shortcut_to_a_specific_profile

• https://developer.mozilla.org/Mozilla/Multiple_Firefox_Profiles

sampson3121 said

Hi, i have always had the option to play youtube videos in 1080 or higher until today. for some reason when i try to play a video that IS 1080p, i don't even get the option to change to anything higher then 720p. i also tried this with Explorer and it's fine. I've tried looking on the net for answers and i can't fix this problem. can you please help me because i would rather use Firefox instead of Internet Explorer...but if i have to i will.

thanks, i tried your solution and it worked :)