Updated the 84 length signature decryption

Updated the right 84 length signature decryption 06.08.2013

youtube_dl/extractor/youtube.py

@@ -188,7 +188,7 @@ class YoutubeIE(InfoExtractor):
         elif len(s) == 85:
             return s[76] + s[82:76:-1] + s[83] + s[75:60:-1] + s[0] + s[59:50:-1] + s[1] + s[49:2:-1]
         elif len(s) == 84:
-            return s[83:36:-1] + s[2] + s[35:26:-1] + s[3] + s[25:3:-1] + s[26]
+            return s[83:27:-1] + s[0] + s[26:5:-1] + s[2:0:-1] + s[27]
         elif len(s) == 83:
             return s[6] + s[3:6] + s[33] + s[7:24] + s[0] + s[25:33] + s[53] + s[34:53] + s[24] + s[54:]
         elif len(s) == 82: