<http://schema.org/topics>
"blip.tv,Facebook,Lists,lunchtime poll,openmyvideo,poll,posterous,qik,Social Media,tubemogul,ustream,veoh,Video,Video Lists,video sharing,Vimeo,YouTube"^^<http://www.w3.org/2001/XMLSchema#string>
<http://mashable.com/2009/12/01/top-10-video-sharing-sites/>