First and foremost, let's just be clear that you don't make a viral video. You make a video,and people make it go viral. The virality (yup I made that up) isn't guaranteed.
Honestly, it's hard for advertisers/brands to get things to go viral because people often see through the BS - unless you're distracted by the Old Spice Guy's rock hard abs.
That being said, here are 10 cool video ads from 2012.
Be inspired!