stack skills not working with youtube-dl

[andrewiassur]

Checklist

• [ x] I'm reporting a broken site support
• I've verified that I'm running youtube-dl version 2019.11.05
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar issues including closed ones

Verbose log

youtube-dl --username <username> --password <password> https://stackskills.com/courses/200998/lectures/3074589 -vvv
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'--username', u'PRIVATE', u'--password', u'PRIVATE', u'https://stackskills.com/courses/200998/lectures/3074589', u'-vvv']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2019.11.05
[debug] Python version 2.7.15+ (CPython) - Linux-5.0.0-35-generic-x86_64-with-Ubuntu-18.04-bionic
[debug] exe versions: ffmpeg 3.4.6, ffprobe 3.4.6, phantomjs 2.1.1, rtmpdump 2.4
[debug] Proxy map: {}
[Teachable] Downloading stackskills.com login page
ERROR: Unable to download webpage: HTTP Error 503: Service Temporarily Unavailable (caused by HTTPError()); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
  File "/usr/local/lib/python2.7/dist-packages/youtube_dl/extractor/common.py", line 627, in _request_webpage
    return self._downloader.urlopen(url_or_request)
  File "/usr/local/lib/python2.7/dist-packages/youtube_dl/YoutubeDL.py", line 2237, in urlopen
    return self._opener.open(req, timeout=self._socket_timeout)
  File "/usr/lib/python2.7/urllib2.py", line 435, in open
    response = meth(req, response)
  File "/usr/lib/python2.7/urllib2.py", line 548, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib/python2.7/urllib2.py", line 467, in error
    result = self._call_chain(*args)
  File "/usr/lib/python2.7/urllib2.py", line 407, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.7/urllib2.py", line 654, in http_error_302
    return self.parent.open(new, timeout=req.timeout)
  File "/usr/lib/python2.7/urllib2.py", line 435, in open
    response = meth(req, response)
  File "/usr/lib/python2.7/urllib2.py", line 548, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib/python2.7/urllib2.py", line 473, in error
    return self._call_chain(*args)
  File "/usr/lib/python2.7/urllib2.py", line 407, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.7/urllib2.py", line 556, in http_error_default
    raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)

Description

youtube-dl --version
2019.11.05
was working up until a few days ago

[remitamine]

duplicate of #20652.