[vevo] The title in the url is optional (fixes #3020)

youtube_dl/extractor/vevo.py

@@ -16,7 +16,7 @@ class VevoIE(InfoExtractor):
     (currently used by MTVIE)
     """
     _VALID_URL = r'''(?x)
-        (?:https?://www\.vevo\.com/watch/(?:[^/]+/[^/]+/)?|
+        (?:https?://www\.vevo\.com/watch/(?:[^/]+/(?:[^/]+/)?)?|
            https?://cache\.vevo\.com/m/html/embed\.html\?video=|
            https?://videoplayer\.vevo\.com/embed/embedded\?videoId=|
            vevo:)