Repository: yt-dlp
Issue: sixx.de: Relaunched website not working
Labels: account-needed,geo-blocked,site-bug

### Checklist

- [X] I'm reporting a broken site
- [X] I've verified that I'm running yt-dlp version **2021.12.01**. ([update instructions](https://github.com/yt-dlp/yt-dlp#update))
- [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](https://github.com/ytdl-org/youtube-dl#video-url-contains-an-ampersand-and-im-getting-some-strange-output-1-2839-or-v-is-not-recognized-as-an-internal-or-external-command)
- [X] I've searched the [bugtracker](https://github.com/yt-dlp/yt-dlp/issues?q=) for similar issues including closed ones. DO NOT post duplicates
- [X] I've read the [guidelines for opening an issue](https://github.com/yt-dlp/yt-dlp/blob/master/CONTRIBUTING.md#opening-an-issue)
- [ ] I've read about [sharing account credentials](https://github.com/yt-dlp/yt-dlp/blob/master/CONTRIBUTING.md#are-you-willing-to-share-account-details-if-needed) and I'm willing to share it if required

### Region

Germany

### Description

sixx.de has been relaunched (new URL: video.sixx.de). The new URLs do not work with yt-dlp. Instead of the video, yt-dlp saves a 4.56KiB file.

Example (new URL, not working with yt-dlp):
https://video.sixx.de/videos/6451797

Example (old URL, same episode, still active and still working with yt-dlp, but with lower video resolution and lower file size):
https://www.sixx.de/tv/sailor-moon/video/238-staffel-2-episode-38-das-ende-von-esmeraude-ganze-folge

A free user account may be needed to watch the video (on the new website as well as on the old one).

By finding out the "playlist.m3u8" URL and using it in the command line, the video can still be downloaded from the new page. However, it would be desirable to adapt the extractor to the new page structure. Presumably, the ProSiebenSat.1 group's other websites (prosieben.de, sat.1.de, kabeleins.de etc.) will also be restructured soon.

### Verbose log

```shell
D:\yt-dlp>yt-dlp -Uv https://video.sixx.de/videos/6451797
[debug] Command-line config: ['-Uv', 'https://video.sixx.de/videos/6451797']
[debug] Encodings: locale cp1252, fs utf-8, out utf-8, err utf-8, pref cp1252
[debug] yt-dlp version 2021.12.01 [91f071a] (win_exe)
[debug] Python version 3.8.10 (CPython 64bit) - Windows-10-10.0.19043-SP0
[debug] exe versions: ffmpeg 3.4.2, rtmpdump 2.5
[debug] Optional libraries: Cryptodome, mutagen, sqlite, websockets
[debug] Proxy map: {}
Latest version: 2021.12.01, Current version: 2021.12.01
yt-dlp is up to date (2021.12.01)
[debug] [generic] Extracting URL: https://video.sixx.de/videos/6451797
[generic] 6451797: Requesting header
WARNING: [generic] Could not send HEAD request to https://video.sixx.de/videos/6451797: HTTP Error 404: Not Found
[generic] 6451797: Downloading webpage
WARNING: [generic] Falling back on generic information extractor.
WARNING: [generic] URL could be a direct video link, returning it as such.
[debug] Default format spec: bestvideo*+bestaudio/best
[info] 6451797: Downloading 1 format(s): 0
[debug] Invoking downloader on "https://video.sixx.de/videos/6451797"
[download] Destination: 6451797 [6451797].unknown_video
[download] 100% of 4.56KiB in 00:01
```