Generic extractor fails to find some video URLs in BDSMLR.com pages (NSFW links)

[Rekrullurker]

Checklist

• I'm reporting a broken site support issue
• I've verified that I'm running youtube-dl version 2020.05.29
• 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 bug reports including closed ones
• I've read bugs section in FAQ

Verbose log

[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-v', 'https://asian-porn-backagian.bdsmlr.com/post/221792446']
[debug] Encodings: locale cp1252, fs mbcs, out cp437, pref cp1252
[debug] youtube-dl version 2020.05.29
[debug] Python version 3.4.4 (CPython) - Windows-XP-5.1.2600-SP3
[debug] exe versions: ffmpeg N-93954-g76ef18fd39
[debug] Proxy map: {}
[generic] 221792446: Requesting header
WARNING: Falling back on generic information extractor.
[generic] 221792446: Downloading webpage
[generic] 221792446: Extracting information
ERROR: Unsupported URL: https://asian-porn-backagian.bdsmlr.com/post/221792446
Traceback (most recent call last):
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpxtvjzx45\build\youtube_dl\YoutubeDL.py", line 797, in extract_info
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpxtvjzx45\build\youtube_dl\extractor\common.py", line 530, in extract
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpxtvjzx45\build\youtube_dl\extractor\generic.py", line 3370, in _real_extract
youtube_dl.utils.UnsupportedError: Unsupported URL: https://asian-porn-backagian.bdsmlr.com/post/221792446

Description

WRITE DESCRIPTION HERE
BDSMLR.com is an adult blogging site, created as an alternative to Tumblr, when Tumblr suddenly decided that it no longer wanted to host adult content. Although images dominate most pages, people will occasionally post short video clips.

BDSMLR isn't directly supported, but YouTube-DL falls back on its generic extractor. Sometimes this works and sometimes it doesn't. I know what causes it to fail (how the video URL is referenced in the page source), but I don't know how to fix it as I don't know anything about programming in Python.

To be honest, I don't know that this IS a bug, but since the video URL can easily be found in the source by simply searching for ".MP4", it seems like YouTube-DL should be able to find it.

Here is a page where YouTube-DL can download the video:

https://asian-porn-backagian.bdsmlr.com/post/221547963

And here is a page where YouTube-DL fails to find anything to download:

https://asian-porn-backagian.bdsmlr.com/post/221792446

It's easy enough to find the video URLs by looking at the page source, then copy and paste them into any downloader, but it's just more convenient to feed the page URL to YouTube-DL and let it find the video on its own.