Suddenly there is no sound on any YouTube video I try to play. Other online videos are fine, whether an alternative to YouTube such as Vimeo or Daily Motion, or media sites.
There is the little x next to the speaker icon at the bottom left of each YouTube, indicating that the sound is switched off. Of course I've clicked on it, but nothing happens, and have also rebooted after updating my Flash.
I'm on a recent MacBook.