My 64bit Win8 machine will direct sound to the default speakers as output but when I try to toggle the sound to a different devices such as e.g. 'headphones' the sound goes out. I am using the notification icons area on my PC to switch the sound output device which works acceptably in other browsers.

The exception I've noticed at least once on a TED talk video was if the sound/movie clip was loaded from the URL directly instead of as embedded in a webpage, the sound device selector native to the OS works fine.