hhmm... Well technically you really can't do that... See the problem with that is, when someone writes their own tutorial, it is them who owns the copyright to that tutorial... So if you want to try to do so, then you would have to include in your Terms of Service, that in submitting any work to your website, they are signing the copyright privileges to you, or your site... You could also have that as an agreement prior to uploading something... Also add that in doing so, relinquishes all their rights as to what they choose to do with their work... Cause otherwise, you can't control something that is not yours to control... If I have the wrong idea of what your trying to do, let me know... Cause I am still a bit confused as to weather or not your wanting this restriction upon those who write the tutorials, or just those who view it..