Browsers identify themselves with a user-agent string, and the user agent strings are a giant disaster of technical debt resulting from a long history of browsers working around buggy websites and websites working around buggy browsers. Browser video is <i>also</i> a giant disaster of technical debt, and YouTube uses the user-agent string to determine which ways of serving video will work and which ones won&#x27;t. Presence of bugs here is no surprise, and any such bugs will naturally impact some browsers but not others.<p>So, a bug in YouTube&#x27;s compatibility-autodetection caused it to fall back to a slower, bitrate-limited fallback method that it didn&#x27;t need to, for some versions of Firefox. They took two weeks to deploy the fix. Considering those two weeks included Christmas and the bug didn&#x27;t affect security or render the site unavailable, this seems like a pretty good response time.