improve generic and encrypted signature error messages

youtube_dl/extractor/common.py

@@ -211,7 +211,7 @@ class InfoExtractor(object):
             raise ExtractorError(u'Unable to extract %s' % _name)
         else:
             self._downloader.report_warning(u'unable to extract %s; '
-                u'please report this issue on GitHub.' % _name)
+                u'please report this issue on http://yt-dl.org/bug' % _name)
             return None
 
     def _html_search_regex(self, pattern, string, name, default=None, fatal=True, flags=0):

youtube_dl/extractor/youtube.py

@@ -129,12 +129,13 @@ class YoutubeIE(InfoExtractor):
         """Indicate the download will use the RTMP protocol."""
         self.to_screen(u'RTMP download detected')
 
-    @staticmethod
-    def _decrypt_signature(s):
+    def _decrypt_signature(self, s):
         """Decrypt the key the two subkeys must have a length of 43"""
         (a,b) = s.split('.')
         if len(a) != 43 or len(b) != 43:
-            raise ExtractorError(u'Unable to decrypt signature, subkeys lengths not valid')
+            raise ExtractorError(u'Unable to decrypt signature, subkeys lengths %d.%d not supported; retrying might work' % (len(a), len(b)))
+        if self._downloader.params.get('verbose'):
+            self.to_screen('encrypted signature length %d.%d' % (len(a), len(b)))
         b = ''.join([b[:8],a[0],b[9:18],b[-4],b[19:39], b[18]])[0:40]
         a = a[-40:]
         s_dec = '.'.join((a,b))[::-1]

youtube_dl/utils.py

@@ -474,7 +474,7 @@ class ExtractorError(Exception):
         """ tb, if given, is the original traceback (so that it can be printed out). """
 
         if not sys.exc_info()[0] in (compat_urllib_error.URLError, socket.timeout, UnavailableVideoError):
-            msg = msg + u'; please report this issue on GitHub.'
+            msg = msg + u'; please report this issue on http://yt-dl.org/bug'
         super(ExtractorError, self).__init__(msg)
 
         self.traceback = tb