def find_favorite_videos_by_username(self, user_name,
                                         orderby='favorite-time',
                                         page=1, count=20):
        """doc: http://open.youku.com/docs/doc?id=54
        """
        url = 'https://openapi.youku.com/v2/videos/favorite/by_user.json'
        params = {
            'client_id': self.client_id,
            'user_name': user_name,
            'orderby': orderby,
            'page': page,
            'count': count
        }
        r = requests.get(url, params=params)
        check_error(r)
        return r.json()
doc: http://open.youku.com/docs/doc?id=54