code: def response_video(self, media_id, title=None, description=None):
          
          self._check_parse()
          title = self._transcoding(title)
          description = self._transcoding(description)
  
          response = VideoReply(message=self.__message, media_id=media_id, title=title, description=description).render()
          return self._encrypt_response(response)
docs: 将 media_id 所代表的视频组装为符合微信服务器要求的响应数据
          :param media_id: 视频的 MediaID
          :param title: 视频消息的标题
          :param description: 视频消息的描述
          :return: 符合微信服务器要求的 XML 响应数据