diff --git a/devscripts/youtube_genalgo.py b/devscripts/youtube_genalgo.py
index fd0120650..31d6ec952 100644
--- a/devscripts/youtube_genalgo.py
+++ b/devscripts/youtube_genalgo.py
@@ -26,9 +26,9 @@ tests = [
     # 84
     ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$%^&*()_-+={[};?>.<",
      "<.>?;}[{=+-_)(*&^%$#@!MNBVCXZASDFGHJKLPOIUYTREWe098765432rmnbvcxzasdfghjklpoiuyt1"),
-    # 83 - vflcaqGO8 2013/07/11
+    # 83 - vflTWC9KW 2013/08/01
     ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!#$%^&*()_+={[};?/>.<",
-     "urty8ioplkjhgfdsazxcvbqm1234567S90QWERTYUIOPLKJHGFDnAZXCVBNM!#$%^&*()_+={[};?/>.<"),
+     "qwertyuioplkjhg>dsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!#$%^&*()_+={[};?/f"),
     # 82
     ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKHGFDSAZXCVBNM!@#$%^&*(-+={[};?/>.<",
      "Q>/?;}[{=+-(*<^%$#@!MNBVCXZASDFGHKLPOIUY8REWT0q&7654321mnbvcxzasdfghjklpoiuytrew9"),
diff --git a/test/test_youtube_sig.py b/test/test_youtube_sig.py
index d06f3c8aa..d645c08fb 100644
--- a/test/test_youtube_sig.py
+++ b/test/test_youtube_sig.py
@@ -52,7 +52,7 @@ class TestYoutubeSig(unittest.TestCase):
 
     def test_83(self):
         wrong = "qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!#$%^&*()_+={[};?/>.<"
-        right = "urty8ioplkjhgfdsazxcvbqm1234567S90QWERTYUIOPLKJHGFDnAZXCVBNM!#$%^&*()_+={[};?/>.<"
+        right = "qwertyuioplkjhg>dsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!#$%^&*()_+={[};?/f"
         self.assertEqual(sig(wrong), right)
 
     def test_82(self):
diff --git a/youtube_dl/extractor/youtube.py b/youtube_dl/extractor/youtube.py
index 31c5bebdc..bc89a14ff 100644
--- a/youtube_dl/extractor/youtube.py
+++ b/youtube_dl/extractor/youtube.py
@@ -346,7 +346,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         elif len(s) == 84:
             return s[83:36:-1] + s[2] + s[35:26:-1] + s[3] + s[25:3:-1] + s[26]
         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:]
+            return s[:15] + s[80] + s[16:80] + s[15]
         elif len(s) == 82:
             return s[36] + s[79:67:-1] + s[81] + s[66:40:-1] + s[33] + s[39:36:-1] + s[40] + s[35] + s[0] + s[67] + s[32:0:-1] + s[34]
         elif len(s) == 81: