
Viral Video is online advertisement by word of mouth. We can see it in Google, Yahoo, and YouTube. It is useful and interesting, but it has also problems. They are an invasion of privacy and copyright. For instance, YouTube became big company because anyone can contribute flash video in the site and see a lot of videos; however, Some company sued YouTube because of invasion of copyright. In fact, Viral Video will be more popular in the future, but new way needs new rules. It is also fact.