Click on a Youtube (any). Video and Audio start correctly, about 5 to 10 seconds later Audio starts again. Now one video, with TWO audios out of sync. Hit mute, only one audio. It is out of sync with video. Any fix? I asked this question to Ubuntu support, Launchpad.net. In back and forth communicating, they concluded, that is in my Firefox settings. I have checked the settings and found nothing to cause this problem. I downloaded an Youtube video to hard drive. It plays correctly from there. (Added 8/8/16)