Firefox HTML 5 disable video and auto play

[KW]

Over the last couple of weeks I have come across several web
sites that autoplay video and audio at full blast using HTML 5. I have
disabled the options in firefox by typing about:config in the browser
then setting this three settings to false:

media.webm.enabled
media.ogg.enabled
media.wave.enabled

Hopefully the makers of Firefox will have an activate switch for all
HTML5 audio and video like they do for flash player.