Hello, I saw you helped athers to find tha anime movies they're were looking for, so maybe you can help and me. So this is what I rememmber: a sad white girl was traped in this boy's castle. The boy had the abbility to turn into a big red ox. And the castle was on this judge clif by the sea.

Any ideas?

The story's a bit different
But it vaguely sounds like,.

The Last Unicorn

The young woman is the one who's been transformed.She
Was a unicorn but a wizard changed her into a human to
Hide her from an evil red bull that hunted unicorns.

-view trailer-

Yes yes, this is it!! Maybe you also know from were I can quikly dowload it?

http://www.tv-links.eu/movies/The-Last-Unicorn_4738/

Or

http://watch-free-movie-online.net/5513_The-Last-Unicorn