About 3.8 million people have now watched Barack Obama's Philadelphia address through the campaign's official YouTube channel, which has over 40,000 subscribers. "It is the highest viewed video ever uploaded by a presidential candidate to YouTube, surpassing Mike Huckabee's Chuck Norris endorsement video," says Steve Grove, who directs News and Politics for YouTube. Aside from the Obama channel, which promotes videos through blogs, news sites and supporter networks, another...