This should illustrate the point more clearly.
http://www.webpronews.com/topnews/20...air-use-rights
Fair Use.
"Fair use is rooted in the first amendment," said Donaldson. "So if you're telling a story, and you need or want, and it's reasonable to use little pieces of other people's stuff to tell that story, that's protected as a first amendment right."
"According to Aufderheide, one thing judges will ask is 'did you use this for a different purpose than the original or are you merely taking something that somebody's actually selling, and getting it for free?' Basically - are you taking market value from them?"
On both of these points the majority of people posting on GFY adhere to fair use.
No one is taking market value from a record company for instance when they post a music video on GFY. Music videos are created and distributed for the purpose of advertising, if you don't know that you should read more.