Viki.com can't download with premium account

[zackmark29]

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

[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['--proxy', '140.82.34.22:3128', '--username', 'PRIVATE', '--password', 'PRIVATE', '-f', 'best', '--get-url', 'https://www.viki.com/videos/168774v-dream-high-2-episode-1', '--verbose', 'flag']
[debug] Encodings: locale cp1252, fs mbcs, out cp437, pref cp1252
[debug] youtube-dl version 2020.03.24
[debug] Python version 3.4.4 (CPython) - Windows-10-10.0.18362
[debug] exe versions: ffmpeg 4.2.2, ffprobe 4.2.2
[debug] Proxy map: {'http': '140.82.34.22:3128', 'https': '140.82.34.22:3128'}
ERROR: Unable to download JSON metadata: HTTP Error 403: Forbidden (caused by HTTPError()); 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.
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpjwbwqymm\build\youtube_dl\extractor\common.py", line 627, in _request_webpage
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpjwbwqymm\build\youtube_dl\YoutubeDL.py", line 2238, in urlopen
  File "C:\Python\Python34\lib\urllib\request.py", line 470, in open
  File "C:\Python\Python34\lib\urllib\request.py", line 580, in http_response
  File "C:\Python\Python34\lib\urllib\request.py", line 508, in error
  File "C:\Python\Python34\lib\urllib\request.py", line 442, in _call_chain
  File "C:\Python\Python34\lib\urllib\request.py", line 588, in http_error_default

Description

I'm still trying to download from viki with legit premium account but always failed even with using a proxy. But I can download with regular account only 480p available

[zackmark29]

What is the missing why it's incomplete? I provided the information