util method for create video params to upload.

        Only need to provide a minimum of two essential parameters:
        title and tags, other video params are optional. All params spec
        see: http://cloud.youku.com/docs?id=110#create .

        Args:
            title: string, 2-50 characters.
            tags: string, 1-10 tags joind with comma.
            description: string, less than 2000 characters.
            copyright_type: string, 'original' or 'reproduced'
            public_type: string, 'all' or 'friend' or 'password'
            watch_password: string, if public_type is password.
            latitude: double.
            longitude: double.
            shoot_time: datetime.

        Returns:
            dict params that upload/create method need.

def prepare_video_params(self, title=None, tags='Others', description='',
                             copyright_type='original', public_type='all',
                             category=None, watch_password=None,
                             latitude=None, longitude=None, shoot_time=None
                             ):
        """ util method for create video params to upload.

        Only need to provide a minimum of two essential parameters:
        title and tags, other video params are optional. All params spec
        see: http://cloud.youku.com/docs?id=110#create .

        Args:
            title: string, 2-50 characters.
            tags: string, 1-10 tags joind with comma.
            description: string, less than 2000 characters.
            copyright_type: string, 'original' or 'reproduced'
            public_type: string, 'all' or 'friend' or 'password'
            watch_password: string, if public_type is password.
            latitude: double.
            longitude: double.
            shoot_time: datetime.

        Returns:
            dict params that upload/create method need.
        """
        params = {}
        if title is None:
            title = self.file_name
        elif len(title) > 80:
            title = title[:80]

        if len(description) > 2000:
            description = description[0:2000]

        params['title'] = title
        params['tags'] = tags
        params['description'] = description
        params['copyright_type'] = copyright_type
        params['public_type'] = public_type
        if category:
            params['category'] = category
        if watch_password:
            params['watch_password'] = watch_password
        if latitude:
            params['latitude'] = latitude
        if longitude:
            params['longitude'] = longitude
        if shoot_time:
            params['shoot_time'] = shoot_time

        return params