Yes. There was a temporary whitelist while Firefox MSE was still in development (to workaround some API incompatibilities on some video sites), but the MSE whitelist was removed in Firefox 42 (November 2015) allow all websites to access the MSE APIs:<p><a href="https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=1185611#c6" rel="nofollow">https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=1185611#c6</a>