Repository: yt-dlp
Issue: Teachertube
Labels: site-bug

### DO NOT REMOVE OR SKIP THE ISSUE TEMPLATE

- [X] I understand that I will be **blocked** if I remove or skip any mandatory\* field

### Checklist

- [X] I'm reporting a new site support request
- [X] I've verified that I'm running yt-dlp version **2023.01.06** ([update instructions](https://github.com/yt-dlp/yt-dlp#update)) or later (specify commit)
- [X] I've checked that all provided URLs are playable in a browser with the same IP and same login details
- [X] I've checked that none of provided URLs [violate any copyrights](https://github.com/yt-dlp/yt-dlp/blob/master/CONTRIBUTING.md#is-the-website-primarily-used-for-piracy) or contain any [DRM](https://en.wikipedia.org/wiki/Digital_rights_management) to the best of my knowledge
- [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 am willing to share it if required

### Region

U.S.

### Example URLs

- https://www.teachertube.com/videos/graphing-quadratic-inequalities-on-desmos-507405 

### Provide a description that is worded well enough to be understood

Teachertube seems like a very simple site. They link to the mp4 file in the html:
```html
<video id="video1_html5_api" class="vjs-tech" preload="auto" poster="https://cdn.teachertube.com//uploads/videos/2021/10/04/507405/desmos-_-graphing-calculator000.jpg" tabindex="-1" src="https://cdn.teachertube.com//uploads/videos/2021/10/04/507405/desmos-_-graphing-calculator.mp4"><p></p><source type="video/mp4" src="https://cdn.teachertube.com//uploads/videos/2021/10/04/507405/desmos-_-graphing-calculator.mp4"></video>
```

### Provide verbose output that clearly demonstrates the problem

- [X] Run **your** yt-dlp command with **-vU** flag added (`yt-dlp -vU <your command line>`)
- [X] Copy the WHOLE output (starting with `[debug] Command-line config`) and insert it below

### Complete Verbose Output

```shell
[debug] Command-line config: ['-vU', 'https://www.teachertube.com/videos/graphing-quadratic-inequalities-on-desmos-507405']
[debug] Encodings: locale cp1252, fs utf-8, pref cp1252, out utf-8, error utf-8, screen utf-8
[debug] yt-dlp version 2023.01.06 [6becd25] (win_exe)
[debug] Python 3.8.10 (CPython AMD64 64bit) - Windows-10-10.0.19045-SP0 (OpenSSL 1.1.1k  25 Mar 2021)
[debug] exe versions: ffmpeg 5.0.1-essentials_build-www.gyan.dev (setts), ffprobe 5.0.1-essentials_build-www.gyan.dev
[debug] Optional libraries: Cryptodome-3.16.0, brotli-1.0.9, certifi-2022.12.07, mutagen-1.46.0, sqlite3-2.6.0, websockets-10.4
[debug] Proxy map: {}
[debug] Loaded 1760 extractors
[debug] Fetching release info: https://api.github.com/repos/yt-dlp/yt-dlp/releases/latest
Latest version: 2023.01.06, Current version: 2023.01.06
yt-dlp is up to date (2023.01.06)
[generic] Extracting URL: https://www.teachertube.com/videos/graphing-quadratic-inequalities-on-desmos-507405
[generic] graphing-quadratic-inequalities-on-desmos-507405: Downloading webpage
WARNING: [generic] Falling back on generic information extractor
[generic] graphing-quadratic-inequalities-on-desmos-507405: Extracting information
[debug] Looking for embeds
ERROR: Unsupported URL: https://www.teachertube.com/videos/graphing-quadratic-inequalities-on-desmos-507405
Traceback (most recent call last):
  File "yt_dlp\YoutubeDL.py", line 1502, in wrapper
  File "yt_dlp\YoutubeDL.py", line 1578, in __extract_info
  File "yt_dlp\extractor\common.py", line 680, in extract
  File "yt_dlp\extractor\generic.py", line 2523, in _real_extract
yt_dlp.utils.UnsupportedError: Unsupported URL: https://www.teachertube.com/videos/graphing-quadratic-inequalities-on-desmos-507405
```