More people are watching online video than ever before, and most share their favorite videos with their friends — but that doesn't mean creating a successful viral video is getting any easier. When we studied the most popular viral videos from the first half of 2010 to learn what type of creative works best, we learned that funny videos are more successful than sexy videos and that the most popular viral videos typically last less than two minutes. Most importantly, we found that interactive marketers should pursue a range of sources for their viral video creative — including user-generated videos and repurposed or extended TV ads.