Repository: youtube-dl
Issue: Site xvideos.com not downloading amateur-channels
Labels: fixed,site-update-request

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## Checklist

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Carefully read and work through this check list in order to prevent the most common mistakes and misuse of youtube-dl:
- First of, make sure you are using the latest version of youtube-dl. Run `youtube-dl --version` and ensure your version is 2021.12.17. If it's not, see https://yt-dl.org/update on how to update. Issues with outdated version will be REJECTED.
- Make sure that all provided video/audio/playlist URLs (if any) are alive and playable in a browser.
- Make sure that all URLs and arguments with special characters are properly quoted or escaped as explained in http://yt-dl.org/escape.
- Search the bugtracker for similar issues: http://yt-dl.org/search-issues. DO NOT post duplicates.
- Read bugs section in FAQ: http://yt-dl.org/reporting
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- [x] I'm reporting a broken site support issue
- [x] I've verified that I'm running youtube-dl version **2021.12.17**
- [x] I've checked that all provided URLs are alive and playable in a browser
- [x] I've checked that all URLs and arguments with special characters are properly quoted or escaped
- [x] I've searched the bugtracker for similar bug reports including closed ones
- [x] I've read bugs section in FAQ


## Verbose log

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Provide the complete verbose output of youtube-dl that clearly demonstrates the problem.
Add the `-v` flag to your command line you run youtube-dl with (`youtube-dl -v <your command line>`), copy the WHOLE output and insert it below. It should look similar to this:
 [debug] System config: []
 [debug] User config: []
 [debug] Command-line args: [u'-v', u'http://www.youtube.com/watch?v=BaW_jenozKcj']
 [debug] Encodings: locale cp1251, fs mbcs, out cp866, pref cp1251
 [debug] youtube-dl version 2021.12.17
 [debug] Python version 2.7.11 - Windows-2003Server-5.2.3790-SP2
 [debug] exe versions: ffmpeg N-75573-g1d0487f, ffprobe N-75573-g1d0487f, rtmpdump 2.4
 [debug] Proxy map: {}
 <more lines>
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```
C:\!Scripts>youtube-dl --verbose flag https://www.xvideos.com/amateur-channels/closeupfantasy#_tabVideos
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['--verbose', 'flag', 'https://www.xvideos.com/amateur-channels/closeupfantasy#_tabVideos']
[debug] Encodings: locale cp1252, fs utf-8, out utf-8, pref cp1252
[debug] youtube-dl version 2021.12.17
[debug] Python version 3.10.6 (CPython) - Windows-10-10.0.19044-SP0
[debug] exe versions: ffmpeg n4.3.1-26-gca55240b8c, ffprobe n4.3.1-26-gca55240b8c, phantomjs 2.1.1
[debug] Proxy map: {}
ERROR: 'flag' is not a valid URL. Set --default-search "ytsearch" (or run  youtube-dl "ytsearch:flag" ) to search YouTube
Traceback (most recent call last):
  File "C:\Users\Test\AppData\Local\Programs\Python\Python310\lib\site-packages\youtube_dl\YoutubeDL.py", line 815, in wrapper
    return func(self, *args, **kwargs)
  File "C:\Users\Test\AppData\Local\Programs\Python\Python310\lib\site-packages\youtube_dl\YoutubeDL.py", line 836, in __extract_info
    ie_result = ie.extract(url)
  File "C:\Users\Test\AppData\Local\Programs\Python\Python310\lib\site-packages\youtube_dl\extractor\common.py", line 534, in extract
    ie_result = self._real_extract(url)
  File "C:\Users\Test\AppData\Local\Programs\Python\Python310\lib\site-packages\youtube_dl\extractor\generic.py", line 2361, in _real_extract
    raise ExtractorError(
youtube_dl.utils.ExtractorError: 'flag' is not a valid URL. Set --default-search "ytsearch" (or run  youtube-dl "ytsearch:flag" ) to search YouTube

```


## Description

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Site xvideos.com not downloading amateur-channels on Windows 10 using youtube_dl-2021.12.17 via Python (tried also using youtube-dl.exe), showing as unsupported URL