I think you're going about it the wrong way.
Seems you're uploading with a simple member account?
They don't provide any links back to your site except the one in your profile.
All members get to use a link on their profile, and get to link it to anywhere they want.
Meaning Xhamster has no control over that, hence the warning page.
You should apply for a content partner account instead.
You get a text link, get to watermark the vid and get a banner spot.
Example video:
http://xhamster.com/movies/1110195/h...er_action.html
http://xhamster.com/movies/638034/ne..._audition.html
Upload 10 min plus, you don't even have to give xhamster credit.
You can just use your ref free site url.
http://xhamster.com/movies/905865/x_...s_in_love.html
http://xhamster.com/movies/1252219/p...bony_anal.html
Not saying I agree with tubes but it is what it is.
Your content will show up there one way or another.
Might as well make sure credit is given where due.