Signature extraction failed on a specific YT video

[LTIOfficial]

• I've verified and I assure that I'm running youtube-dl 2018.11.03

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)

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[debug] System config: [u'--ignore-errors', u'-o', u'/files/public/ytdl/%(title)s-%(id)s.%(ext)s']
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-vF', u'a36_CwzA0bk']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2018.11.03
[debug] Python version 2.7.5 (CPython) - Linux-3.10.0-862.14.4.el7.x86_64-x86_64-with-centos-7.5.1804-Core
[debug] exe versions: ffmpeg 2.8.15, ffprobe 2.8.15
[debug] Proxy map: {}
[youtube] a36_CwzA0bk: Downloading webpage
[youtube] a36_CwzA0bk: Downloading video info webpage
[youtube] {43} signature length 41.41, html5 player vfls4aurX
[youtube] a36_CwzA0bk: Downloading player https://www.youtube.com/yts/jsbin/player-vfls4aurX/en_US/base.js
ERROR: Signature extraction failed: Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1221, in _decrypt_signature
    video_id, player_url, s
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1130, in _extract_signature_function
    res = self._parse_sig_js(code)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1193, in _parse_sig_js
    jscode, 'Initial JS player signature function name', group='sig')
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 983, in _search_regex
    raise RegexNotFoundError('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 . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
 (caused by RegexNotFoundError(u'Unable to extract \x1b[0;34mInitial JS player signature function name\x1b[0m; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.',)); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1221, in _decrypt_signature
    video_id, player_url, s
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1130, in _extract_signature_function
    res = self._parse_sig_js(code)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1193, in _parse_sig_js
    jscode, 'Initial JS player signature function name', group='sig')
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 983, in _search_regex
    raise RegexNotFoundError('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 . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 792, in extract_info
    ie_result = ie.extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 508, in extract
    ie_result = self._real_extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1814, in _real_extract
    encrypted_sig, video_id, player_url, age_gate)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1231, in _decrypt_signature
    'Signature extraction failed: ' + tb, cause=e)
ExtractorError: Signature extraction failed: Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1221, in _decrypt_signature
    video_id, player_url, s
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1130, in _extract_signature_function
    res = self._parse_sig_js(code)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1193, in _parse_sig_js
    jscode, 'Initial JS player signature function name', group='sig')
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 983, in _search_regex
    raise RegexNotFoundError('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 . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
 (caused by RegexNotFoundError(u'Unable to extract \x1b[0;34mInitial JS player signature function name\x1b[0m; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.',)); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
<end of log>

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Description of the issue:

The following commands only seem to fail on this particular YouTube video, while numerous other videos succeed without incident.

I initially tried this download command, which uses ffmpeg to combine the best mp4 and m4a available into a resulting 'best mp4':
# youtube-dl -f 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/mp4' a36_CwzA0bk

I then tried passing the full YouTube URL, which also failed. I then tried a simple query to see if maybe mp4 was not an available format for some reason. The log above is from this last command, with the addition of the -v option.

# youtube-dl -vF a36_CwzA0bk

[scottbeebiwan]

have same problems with (seems like) videos from early 2017 or 2015
example: watch?v=WI-SCFlUfns

[LTIOfficial]

For whatever it's worth, the video I am having difficulties with was uploaded to YT back in 2011.

[scottbeebiwan]

Huh... It seems SOMETIMES it can download videos when they may have this error. I got it to download a video once but it decided to have this error a couple minutes later.