This is a topic with which I have been deeply interested myself. I am a performance enthusiast / efficient computing kinda guy. I specialize in optimizing software to suit hardware.
One app of a particular lightweight dist I've taken a love to is a GTk-based youtube browser. Featured in ANTIX Linux. It is more or less a single-paged superquick youtube.com meta searcher - which itself inturn launches MPLAYER at the request of any listed video.
This entire setup intrigued me as it got me thinking about the bit of code the programmer(s) used to get their GTK youtube searcher to pass an URL/steaming media to mplayer.
In that line of investigation, I stumbled across this::
http://www.commandlinefu.com/commands/view/1405/stream-youtube-url-directly-to-mplayer.
And there, voila, a bit code resembling that which likely was used with this youtube-browser app that comes in Antix Linux (Great distro).