t_mann,
First, he is using the Line "
Copy from http://xtutorials.net", so he is not actually claiming the right, is he?

Though what he is doing is not right, since he is doing this behind your back, and without your consent.
Now, if you are using any cPanel host for your site, then you can easily stop the BandWidth Steal. Go to cPanel and find security tab and
HotLink Protection . Use that to disallow file type and allowed site like yours and any other. This feature is done especially to prevent BandWidth steal. Video tutorial should be there for any further help.
I am not sure how to contact the publisher. But you might try to make a post in his recent tutorial that was yours

. Ask him to contact you. You should contact blogger team if he fails to contact you. Anyway I hope you'll get this sorted soon.
CHEERS!