Originally Posted by notime

Either it's legal content or it's not.

If a private person uploads his/her OWN content AND gives permission (and if needed by local law; copy ID / modelrelease): then=legal if age>18 (depending on country)

If anybody else uploads/adds it (wether the owner, a paid uploader or consumer uploader)..the question is did the model(s)/producer(s)/studio(s)/Broker(s)/affiliate program(s) give (written) permission to do so: yes or no ?

There is your anwer.

(some countries have flaws in the laws and it's not dealt with 100% legally as in the 10 commandments; "thy shall not steal" for example)