diff --git a/modules/youtube/pages.py b/modules/youtube/pages.py
index 1f46936f..4ab61d4e 100644
--- a/modules/youtube/pages.py
+++ b/modules/youtube/pages.py
@@ -97,6 +97,33 @@ class VideoPage(BaseYoutubePage):
         45: 'webm',
     }
 
+    def _decrypt_signature(self, s):
+        """Turn the encrypted s field into a working signature"""
+
+        if len(s) == 92:
+            return s[25] + s[3:25] + s[0] + s[26:42] + s[79] + s[43:79] + s[91] + s[80:83]
+        elif len(s) == 90:
+            return s[25] + s[3:25] + s[2] + s[26:40] + s[77] + s[41:77] + s[89] + s[78:81]
+        elif len(s) == 88:
+            return s[48] + s[81:67:-1] + s[82] + s[66:62:-1] + s[85] + s[61:48:-1] + s[67] + s[47:12:-1] + s[3] + s[11:3:-1] + s[2] + s[12]
+        elif len(s) == 87:
+            return s[62] + s[82:62:-1] + s[83] + s[61:52:-1] + s[0] + s[51:2:-1]
+        elif len(s) == 86:
+            return s[2:63] + s[82] + s[64:82] + s[63]
+        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:
+            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:]
+        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:
+            return s[6] + s[3:6] + s[33] + s[7:24] + s[0] + s[25:33] + s[2] + s[34:53] + s[24] + s[54:81]
+
+        else:
+            raise BrokenPageError(u'Unable to decrypt signature, key length %d not supported; retrying might work' % (len(s)))
+
     def get_video_url(self, format=38):
         formats = {}
         for script in self.parser.select(self.document.getroot(), 'script'):
@@ -114,7 +141,12 @@ class VideoPage(BaseYoutubePage):
 
             for part in a['args']['url_encoded_fmt_stream_map'].split(','):
                 args = dict(parse_qsl(part))
-                formats[int(args['itag'])] = args['url'] + '&signature=' + args['sig']
+                url = args['url']
+                if 'sig' in args:
+                    signature = args['sig']
+                elif 's' in args:
+                    signature = self._decrypt_signature(args['s'])
+                formats[int(args['itag'])] = args['url'] + '&signature=' + signature
 
             break