Trying to play Widevine with no Windows Media Foundation (nor Silverlight fallback), see https://support.mozilla.org/kb/fix-video-audio-problems-firefox-windows
Опит за възпроизвеждане на Widevine без Windows Media Foundation и без Silverlight за резерва, вижте https://support.mozilla.org/kb/fix-video-audio-problems-firefox-windows