Added RDMM back

Eg: https://www.youtube.com/watch?v=MuAGGZNfUkU&list=RDMM

youtube_dlc/extractor/youtube.py

@@ -72,7 +72,7 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
     # If True it will raise an error if no login info is provided
     _LOGIN_REQUIRED = False
 
-    _PLAYLIST_ID_RE = r'(?:(?:PL|LL|EC|UU|FL|RD|UL|TL|PU|OLAK5uy_)[0-9A-Za-z-_]{10,})'
+    _PLAYLIST_ID_RE = r'(?:(?:PL|LL|EC|UU|FL|RD|UL|TL|PU|OLAK5uy_)[0-9A-Za-z-_]{10,}|RDMM)'
 
     _YOUTUBE_CLIENT_HEADERS = {
         'x-youtube-client-name': '1',