diff --git a/devscripts/youtube_genalgo.py b/devscripts/youtube_genalgo.py
index 22977ccd90..fd01206506 100644
--- a/devscripts/youtube_genalgo.py
+++ b/devscripts/youtube_genalgo.py
@@ -17,9 +17,9 @@
     # 87 - vflART1Nf 2013/07/24
     ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$^&*()_-+={[]}|:;?/>.<",
      "tyuioplkjhgfdsazxcv<nm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$^&*()_-+={[]}|:;?/>"),
-    # 86 - vfl_ymO4Z 2013/06/27
+    # 86 - vflm_D8eE 2013/07/31
     ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$%^&*()_-+={[|};?/>.<",
-     "ertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!/#$%^&*()_-+={[|};?@"),
+     ">.1}|[{=+-_)(*&^%$#@!MNBVCXZASDFGHJK<POIUYTREW509876L432/mnbvcxzasdfghjklpoiuytre"),
     # 85 - vflSAFCP9 2013/07/19
     ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$%^&*()_-+={[};?/>.<",
      "ertyuiqplkjhgfdsazx$vbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#<%^&*()_-+={[};?/c"),
@@ -40,6 +40,12 @@
      "Z?;}[{=+-(*&^%$#@!MNBVCXRASDFGHKLPOIUYT/EWQ0q87659321mnbvcxzasdfghjkl4oiuytrewp"),
 ]
 
+tests_age_gate = [
+    # 86 - vflqinMWD
+    ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$%^&*()_-+={[|};?/>.<",
+     "ertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!/#$%^&*()_-+={[|};?@"),
+]
+
 def find_matching(wrong, right):
     idxs = [wrong.index(c) for c in right]
     return compress(idxs)
@@ -90,6 +96,8 @@ def genall(tests):
 
 def main():
     print(genall(tests))
+    print(u'    Age gate:')
+    print(genall(tests_age_gate))
 
 if __name__ == '__main__':
     main()
diff --git a/test/test_youtube_sig.py b/test/test_youtube_sig.py
index 4d45a0e08c..d06f3c8aa5 100644
--- a/test/test_youtube_sig.py
+++ b/test/test_youtube_sig.py
@@ -10,7 +10,9 @@
 from youtube_dl.extractor.youtube import YoutubeIE
 from helper import FakeYDL
 
-sig = YoutubeIE(FakeYDL())._decrypt_signature
+ie = YoutubeIE(FakeYDL())
+sig = ie._decrypt_signature
+sig_age_gate = ie._decrypt_signature_age_gate
 
 class TestYoutubeSig(unittest.TestCase):
     def test_92(self):
@@ -35,7 +37,7 @@ def test_87(self):
 
     def test_86(self):
         wrong = "qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$%^&*()_-+={[|};?/>.<"
-        right = "ertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!/#$%^&*()_-+={[|};?@"
+        right = ">.1}|[{=+-_)(*&^%$#@!MNBVCXZASDFGHJK<POIUYTREW509876L432/mnbvcxzasdfghjklpoiuytre"
         self.assertEqual(sig(wrong), right)
 
     def test_85(self):
@@ -67,6 +69,11 @@ def test_79(self):
         wrong = "qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKHGFDSAZXCVBNM!@#$%^&*(-+={[};?/"
         right = "Z?;}[{=+-(*&^%$#@!MNBVCXRASDFGHKLPOIUYT/EWQ0q87659321mnbvcxzasdfghjkl4oiuytrewp"
         self.assertEqual(sig(wrong), right)
+    
+    def test_86_age_gate(self):
+        wrong = "qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$%^&*()_-+={[|};?/>.<"
+        right = "ertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!/#$%^&*()_-+={[|};?@"
+        self.assertEqual(sig_age_gate(wrong), right)
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/youtube_dl/extractor/youtube.py b/youtube_dl/extractor/youtube.py
index f10f2e3dd9..ba8fdfdf2e 100644
--- a/youtube_dl/extractor/youtube.py
+++ b/youtube_dl/extractor/youtube.py
@@ -286,7 +286,7 @@ def _decrypt_signature(self, s):
         elif len(s) == 87:
             return s[4:23] + s[86] + s[24:85]
         elif len(s) == 86:
-            return s[2:63] + s[82] + s[64:82] + s[63]
+            return s[83:85] + s[26] + s[79:46:-1] + s[85] + s[45:36:-1] + s[30] + s[35:30:-1] + s[46] + s[29:26:-1] + s[82] + s[25:1:-1]
         elif len(s) == 85:
             return s[2:8] + s[0] + s[9:21] + s[65] + s[22:65] + s[84] + s[66:82] + s[21]
         elif len(s) == 84:
@@ -303,6 +303,16 @@ def _decrypt_signature(self, s):
         else:
             raise ExtractorError(u'Unable to decrypt signature, key length %d not supported; retrying might work' % (len(s)))
 
+    def _decrypt_signature_age_gate(self, s):
+        # The videos with age protection use another player, so the algorithms
+        # can be different.
+        if len(s) == 86:
+            return s[2:63] + s[82] + s[64:82] + s[63]
+        else:
+            # Fallback to the other algortihms
+            self._decrypt_signature(s)
+
+
     def _get_available_subtitles(self, video_id):
         self.report_video_subtitles_download(video_id)
         request = compat_urllib_request.Request('http://video.google.com/timedtext?hl=en&type=list&v=%s' % video_id)
@@ -611,7 +621,11 @@ def _real_extract(self, url):
                             parts_sizes = u'.'.join(compat_str(len(part)) for part in s.split('.'))
                             self.to_screen(u'encrypted signature length %d (%s), itag %s, %s' %
                                 (len(s), parts_sizes, url_data['itag'][0], player))
-                        signature = self._decrypt_signature(url_data['s'][0])
+                        encrypted_sig = url_data['s'][0]
+                        if age_gate:
+                            signature = self._decrypt_signature_age_gate(encrypted_sig)
+                        else:
+                            signature = self._decrypt_signature(encrypted_sig)
                         url += '&signature=' + signature
                     if 'ratebypass' not in url:
                         url += '&ratebypass=yes'