60fps settings on youtube are set by youtube. Firefox has no bearing on when or if they will be available for certain platforms and settings.

You need to wait until a Firefox version gets released that has MSE support enabled by default. *[/questions/1028307] Will Firefox support Youtube in 60 fps anytime soon? You can find the Polish version of the current Nightly build here: *http://download.cdn.mozilla.net/pub/mozilla.org/firefox/nightly/latest-mozilla-central-l10n/ Nightly alpha builds can be unstable at times and prone to crash, so always install such an alpha version as an extra browser alongside of the current stable release and use the Nightly build for testing purposes. Make sure to create a separate profile folder for each version. See: *https://developer.mozilla.org/Mozilla/Multiple_Firefox_Profiles *http://kb.mozillazine.org/Creating_a_new_Firefox_profile_on_Windows *http://kb.mozillazine.org/Shortcut_to_a_specific_profile *http://kb.mozillazine.org/Using_multiple_profiles_-_Firefox