Repository: youtube-dl
Issue: [ARD:mediathek] Unable to extract media id
Labels: broken-IE

## Checklist

- [x] I'm reporting a broken site support
- [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
(the URL is alive as of now, but it might be taken down at some point)
- [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 issues including closed ones
(there were multiple similar issues for other URLs, but these are marked as fixed, while the currently encountered error is still there)


## Verbose log

```
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['--verbose', 'https://www.ardmediathek.de/video/tom-sawyer/24-wie-tom-ein-rudel-woelfe-baendigte/kika/MDdkMjc0ZmYtOWJkNi00ZTg0LTlkMDUtMzAzYzI3YjRlOGZh?isChildContent']
[debug] Encodings: locale UTF-8, fs utf-8, out utf-8, pref UTF-8
[debug] youtube-dl version 2021.12.17
[debug] Git HEAD: 86e3cf5e5
[debug] Python 3.10.12 (CPython x86_64 64bit) - Linux-5.15.0-78-generic-x86_64-with-glibc2.35 - OpenSSL 3.0.2 15 Mar 2022 - glibc 2.35
[debug] exe versions: ffmpeg 4.4.2, ffprobe 4.4.2, phantomjs ., rtmpdump 2.4
[debug] Proxy map: {'no': 'localhost,127.0.0.0/8,::1'}
[debug] Using fake IP 53.53.132.33 (DE) as X-Forwarded-For.
[ARD:mediathek] MDdkMjc0ZmYtOWJkNi00ZTg0LTlkMDUtMzAzYzI3YjRlOGZh: Downloading webpage
ERROR: Unable to extract media id; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "/tmp/youtube-dl/youtube_dl/YoutubeDL.py", line 859, in wrapper
    return func(self, *args, **kwargs)
  File "/tmp/youtube-dl/youtube_dl/YoutubeDL.py", line 955, in __extract_info
    ie_result = ie.extract(url)
  File "/tmp/youtube-dl/youtube_dl/extractor/common.py", line 565, in extract
    ie_result = self._real_extract(url)
  File "/tmp/youtube-dl/youtube_dl/extractor/ard.py", line 235, in _real_extract
    video_id = self._search_regex(
  File "/tmp/youtube-dl/youtube_dl/extractor/common.py", line 1045, in _search_regex
    raise RegexNotFoundError('Unable to extract %s' % _name)
youtube_dl.utils.RegexNotFoundError: Unable to extract media id; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
```

## Description

The video URL https://www.ardmediathek.de/video/tom-sawyer/24-wie-tom-ein-rudel-woelfe-baendigte/kika/MDdkMjc0ZmYtOWJkNi00ZTg0LTlkMDUtMzAzYzI3YjRlOGZh?isChildContent (and other ones from https://www.ardmediathek.de/sendung/tom-sawyer/Y3JpZDovL2hyLW9ubGluZS8zODIyMDEwNA?isChildContent as far as already tried) don't work, while they are perfectly playable e.g. from a Firefox browser. This hinders playback from CLI players like `mpv`.

Any hints on how to investigate this further are appreciated.