CC and Copyright - Please Answer!

Im going to be making a documentary on the dark side of sims cc (not as in things that break the sims T rating, but unethical cc sites that steal their content and other bad things.) It will be on youtube on my channel FreezysForever but I have a question for something - Does anyone know any cases when cc would have copyright applied? For example, do any cc creators you know put copyright on their cc? Do certain sites like TSR and SimFileShare apply copyright or trademark to the works posted there? Basically, would there be a case where reposting or reuploading cc without it simply being a "retweet/share" sorta dealio be illegal?