PornHubPremium does not work because my Authentication is not recognized

[FredLeigh]

Checklist

• I'm reporting a broken site support
• I've verified that I'm running youtube-dl version 2020.03.24
• 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

PASTE VERBOSE LOG HERE

Description

Hello,

I have a PornHub Premium account. When I try to download a Premium video, YouTube-dl tells me "PornHub Premium requires authentication", despite me having added my login and pass correctly. What can I do to fix this?

I typed everything correctly, like this:
youtube-dl -u XXUSERNAMEXX -p XXPASSWORDXX --verbose XXPornHubPremium.comURLXX
I've retyped my username and password many times making sure it is entered correctly, and tried 10+ different Pornhub Premium links. Each time, I get the same error.

This is the verbose output:

[debug] System config: [u'-o', u'~/Downloads/%(title)s.%(ext)s']
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-u', u'PRIVATE', u'-p', u'PRIVATE', u'--verbose', u'https://www.pornhubpremium.com/view_video.php?viewkey=ph5e6b2e40a32b6']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2020.03.24
[debug] Python version 2.7.16 (CPython) - Darwin-19.3.0-x86_64-i386-64bit
[debug] exe versions: none
[debug] Proxy map: {}
ERROR: PornHub Premium requires authentication. You may want to use --cookies.
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 797, in extract_info
    ie_result = ie.extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 530, in extract
    ie_result = self._real_extract(url)
  File "/usr/local/bin/youtube-dl/youtube_dl/extractor/pornhub.py", line 177, in _real_extract
    expected=True)
ExtractorError: PornHub Premium requires authentication. You may want to use --cookies.