Unable to extract Initial JS player signature function name;

[vfatelinux]

youtube-dl -v -f 18 'https://www.youtube.com/watch?v=51vQo-imc4Q'

[debug] System config: []
[debug] User config: []
[debug] Command-line args: ['-v', '-f', '18', 'https://www.youtube.com/watch?v=5
1vQo-imc4Q']
[debug] Encodings: locale 'UTF-8', fs 'UTF-8', out 'UTF-8', pref: 'UTF-8'
[debug] youtube-dl version 2014.02.17
[debug] Python version 2.7.6 - Linux-3.13.0-29-generic-x86_64-with-Ubuntu-14.04-
trusty
[debug] Proxy map: {}
[youtube] Setting language
[youtube] 51vQo-imc4Q: Downloading webpage
[youtube] 51vQo-imc4Q: Downloading video info webpage
[youtube] 51vQo-imc4Q: Extracting video information
[youtube] 51vQo-imc4Q: Encrypted signatures detected.
[youtube] encrypted signature length 82 (40.41), itag 22, html5 player en_US-vfl
gt97Vg
[youtube] 51vQo-imc4Q: Downloading js player vflgt97Vg
WARNING: Automatic signature extraction failed: Traceback (most recent call last
):
File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line
957, in _decrypt_signature
video_id, player_url, len(s)
File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line
356, in _extract_signature_function
res = self._parse_sig_js(code)
File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line
424, in _parse_sig_js
u'Initial JS player signature function name')
File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/common.py", line 3
56, in _search_regex
raise RegexNotFoundError(u'Unable to extract %s' % _name)
RegexNotFoundError: Unable to extract Initial JS player signature function name;
please report this issue on https://yt-dl.org/bug . Be sure to call youtube-dl
with the --verbose flag and include its complete output. Make sure you are using
the latest version; type youtube-dl -U to update.

WARNING: Warning: Falling back to static signature algorithm
[youtube] encrypted signature length 82 (40.41), itag 43, html5 player en_US-vfl
gt97Vg
[youtube] 51vQo-imc4Q: Downloading js player vflgt97Vg
WARNING: Automatic signature extraction failed: Traceback (most recent call last
):
File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line
957, in _decrypt_signature
video_id, player_url, len(s)
File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line
356, in _extract_signature_function
res = self._parse_sig_js(code)
File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line
424, in _parse_sig_js
u'Initial JS player signature function name')
File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/common.py", line 3
56, in _search_regex
raise RegexNotFoundError(u'Unable to extract %s' % _name)
RegexNotFoundError: Unable to extract Initial JS player signature function name;
please report this issue on https://yt-dl.org/bug . Be sure to call youtube-dl
with the --verbose flag and include its complete output. Make sure you are using
the latest version; type youtube-dl -U to update.

WARNING: Warning: Falling back to static signature algorithm
[youtube] encrypted signature length 82 (40.41), itag 18, html5 player en_US-vfl
gt97Vg
[youtube] 51vQo-imc4Q: Downloading js player vflgt97Vg

[dstftw]

Duplicate of #3104. This issue was fixed in c26e9ac, run sudo youtube-dl -U to upgrade.