WashingtonPost.comBy Jose Antonio VargasSunday, December 28, 2008It was through news clips posted on YouTube -- and through Obama's YouTube channel, which lists more than 1,800 videos -- that groups [of people] learned about the Illinois senator's policies and positions.And it was mostly on the Internet, in one of those ubiquitous, inescapable Web ads -- the campaign spent $8 million on online adv