> ExtractorError: Signature extraction failed: Traceback (most recent call last):>

 "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 658, in _decrypt_signature
WARNING: Automatic signature extraction failed: Traceback (most recent call last):

 "/opt/youtube-dl/youtube-dl/youtube_dl/extractor/youtube.py", line 1026, in _decrypt_signature
video_id, player_url, len(s)

 "/opt/youtube-dl/youtube-dl/youtube_dl/extractor/youtube.py", line 426, in _extract_signature_function
errnote=u'Download of %s failed' % player_url)

 "/opt/youtube-dl/youtube-dl/youtube_dl/extractor/common.py", line 205, in _download_webpage
return self._download_webpage_handle(url_or_request, video_id, note, errnote)[0]

 "/opt/youtube-dl/youtube-dl/youtube_dl/extractor/common.py", line 168, in _download_webpage_handle
urlh = self._request_webpage(url_or_request, video_id, note, errnote)

 "/opt/youtube-dl/youtube-dl/youtube_dl/extractor/common.py", line 155, in _request_webpage
return compat_urllib_request.urlopen(url_or_request)

 "/usr/lib/python2.7/urllib2.py", line 126, in urlopen
return _opener.open(url, data, timeout)

 "/usr/lib/python2.7/urllib2.py", line 392, in open
protocol = req.get_type()

 "/usr/lib/python2.7/urllib2.py", line 254, in get_type
raise ValueError, "unknown url type: %s" % self.__originalValueError: unknown url type: //s.ytimg.com/yts/jsbin/html5player-vflG49soT.js