Downloading private video from youtube is broken

[benderillo]

• [X ] I've verified and I assure that I'm running youtube-dl 2019.04.01
• [X ] At least skimmed through the README, most notably the FAQ and BUGS sections
• [ X] Searched the bugtracker for similar issues including closed ones
• [ X] Checked that provided video/audio/playlist URLs (if any) are alive and playable in a browser

What is the purpose of your issue?

• [X ] Bug report (encountered problems with youtube-dl)
• Site support request (request for adding support for a new site)
• Feature request (request for a new functionality)
• Question
• Other

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[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-v', u'-u', u'PRIVATE', u'-p', u'PRIVATE', u'-f', u'mp4', u'https://www.youtube.com/watch?v=mvx8l-z0ipI&feature=youtu.be']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2019.04.01
[debug] Python version 2.7.14 (CPython) - Darwin-18.5.0-x86_64-i386-64bit
[debug] exe versions: ffmpeg 4.1.1, ffprobe 4.1.1, rtmpdump 2.4
[debug] Proxy map: {}
[youtube] Downloading login page
[youtube] Looking up account info
[youtube] Logging in
Type 2-step verification code and press [Return]:
[youtube] Submitting TFA code
[youtube] Checking cookie
[youtube] mvx8l-z0ipI: Downloading webpage
[youtube] mvx8l-z0ipI: Downloading video info webpage
WARNING: Unable to extract video title
ERROR: This video is unavailable.
Traceback (most recent call last):
File "./youtube-dl/youtube_dl/YoutubeDL.py", line 796, in extract_info
ie_result = ie.extract(url)
File "./youtube-dl/youtube_dl/extractor/common.py", line 529, in extract
ie_result = self._real_extract(url)
File "./youtube-dl/youtube_dl/extractor/youtube.py", line 1982, in _real_extract
raise ExtractorError(error_message, expected=True)
ExtractorError: This video is unavailable.

Description of your issue, suggested solution and other information

The video referenced in this issue is private and available for playback in browser under my youtube account.

Downloading it used to work few days ago.
Today I tried to download, and it no longer works.
Apparently, youtube have changed something so the private videos are not downloadable any more.