[cbs] Modernize

youtube_dl/extractor/cbs.py

@@ -1,7 +1,5 @@
 from __future__ import unicode_literals
 
-import re
-
 from .common import InfoExtractor
 
 
@@ -39,8 +37,7 @@ class CBSIE(InfoExtractor):
     }]
 
     def _real_extract(self, url):
-        mobj = re.match(self._VALID_URL, url)
-        video_id = mobj.group('id')
+        video_id = self._match_id(url)
         webpage = self._download_webpage(url, video_id)
         real_id = self._search_regex(
             r"video\.settings\.pid\s*=\s*'([^']+)';",