video_id, display_id = re.match(self._VALID_URL, url).groups()
# the video may come from an external site
- m_external = re.match('^(\w{2})-(.*)$', video_id)
+ m_external = re.match(r'^(\w{2})-(.*)$', video_id)
if m_external is not None:
prefix, ext_id = m_external.groups()
# Check if video comes from YouTube