'display_id': 'petite-asian-lady-mai-playing-in-bathtub',
             'ext': 'mp4',
             'title': 'Petite Asian Lady Mai Playing In Bathtub',
-            'thumbnail': 're:^https?://.*\.jpg$',
+            'thumbnail': r're:^https?://.*\.jpg$',
             'view_count': int,
             'age_limit': 18,
         }
     def _extract_info(self, url):
         mobj = re.match(self._VALID_URL, url)
         video_id = mobj.group('id')
-        display_id = mobj.group('display_id') or video_id
+        display_id = (mobj.group('display_id')
+                      if 'display_id' in mobj.groupdict()
+                      else None) or mobj.group('id')
 
         webpage = self._download_webpage(
             url, display_id, headers={'Cookie': 'age_verified=1'})