comScore has released online video data for December 2008, and, as expected, Google-owned YouTube continued to dominate the field. YouTube accounts for 99 percent of video viewing on Google sites, which saw almost 6 billion video views in December.
YouTube saw over 100 million unique visitors, a milestone first achieved in October 2008. The total number of unique video viewers was 150 million, meaning 2 out of 3 uniques visit YouTube. (Keep in mind, people can visit more than one site, of course.)