At the moment there is a bug with supportsMuting() under the following scenario: 1. setMuted() is called on the HTMLMediaElement before the MediaPlayer is constructed in loadResource(). m_muted in HTMLMediaElement is set to true, but nothing else of interest happens. 2. The MediaPlayer is contructed during loadResource and updateVolume() is called. updateVolume() assumes that supportsMuting() == false, and sets the volume of the MediaPlayer to 0 (because m_muted is true). 3. MediaPlayer loads a media engine which supports muting. Subsequent calls to supportsMuting() will return true. 4. Attempting to unmute the media element at this point is unsuccessful. MediaPlayer::m_muted changes, but MediaPlayer::m_volume is still zero. This can be solved by making sure that HTMLMediaElement::updateVolume() checks for supportsMuting(), and moving the call to updateVolume() in loadResource() to after the call to load() (i.e. Media Engine Selection). HOWEVER, I don't believe this is the correct solution. Why are we exposing supportsMuting() to HTMLMediaElement at all? This should be interface which exists only between MediaPlayer and MediaPlayerPrivate. Patch forthcoming.