A tearful Britney Spears fan and a lustful Barack Obama supporter are among this year's YouTube stars, according to the video sharing site.

While Chris Crocker's "Leave Britney Alone" post registered more than 14 million views and Barely Political's "Obama Girl" had more than 4 million views on YouTube, the site counted both videos as among its greatest hits of 2007 based on a number of factors. According to a Reuters report, officials at YouTube combined total views with comments, favorites and shares to determine the hottest properties on the site.

Curiously, neither video includes any advertising. YouTube, which launched advertising for a few producers in May, expanded its program to include all posters earlier this month. 

"Battle at Kruger," a homemade nature documentary depicting a fierce wildlife struggle between lions, water buffaloes and crocodiles over a young calf, had 21 million views this year -- the most of any YouTube video. While its producer, Jason Schlosberg, has managed to parlay his video into a documentary for National Geographic, the YouTube post has yet to be monetized.