In case you're wondering, it appears that the volume control on the video player goes to eleven. There's a hacker somewhere in the BBC with a sense of humor.
It has always gone up to 11, ever since the flash version of the iplayer first started its beta. It makes me smile that they have still managed to keep it, this many meetings later :)
This is the kind of 'eccentric' stuff that british people self-consciously obsess over though. As a nation we think it makes us 'interesting.' I imagine if they did change it so it only went to 10, they would be inundated with more letters of complaint than they could open, both ironic and terrifyingly serious.