docs: def _extract_id(self) -> str:
          """
          Get video_id needed to obtain the real_url of the video.
  
          Raises:
              VideoIdNotMatchedError: If video_id is not matched with regular expression.
  
          """
          match = re.match(self._VALID_URL, self.url)
  
          if match:
              return match.group('video_id')
          else:
              raise VideoIdNotMatchedError