Repository: yt-dlp
Issue: Site feature request: Substack newsletter post type to download embedded videos from newsletter pages
Labels: site-enhancement,triage

### DO NOT REMOVE OR SKIP THE ISSUE TEMPLATE

- [X] I understand that I will be **blocked** if I *intentionally* remove or skip any mandatory\* field

### Checklist

- [X] I'm requesting a feature unrelated to a specific site
- [X] I've looked through the [README](https://github.com/yt-dlp/yt-dlp#readme)
- [X] I've verified that I'm running yt-dlp version **2023.07.06** ([update instructions](https://github.com/yt-dlp/yt-dlp#update)) or later (specify commit)
- [X] I've searched [known issues](https://github.com/yt-dlp/yt-dlp/issues/3766) and 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)

### Provide a description that is worded well enough to be understood

I need to download videos from newsletter post types. If someone can help make it happen I would be very grateful!

https://github.com/yt-dlp/yt-dlp/issues/7880#issuecomment-1688019146

- What the problem is: yt-dlp doesn't support newsletter Page type from substack.com website
- How it could be fixed: need to add substack newsletter page type extractor 
- How your proposed solution would look like: Not sure what it will look like. I'd have to look at some of the existing extractors to see how to craft my own solution https://github.com/yt-dlp/yt-dlp/blob/master/CONTRIBUTING.md#adding-support-for-a-new-site. I see that someone tried to do this and they made a pull request but I'm not sure that made it into the current version of yt-dlp or what the reason is for why it didn't make it into the current version https://github.com/yt-dlp/yt-dlp/pull/4011

Since each newsletter page can have multiple videos embedded in it, I'm thinking we could treat it as a playlist page from youtube for example and download all the videos from a newsletter page type like we would download all the videos from a youtube playlist.

Thank you for taking the time to look into this and for trying to help provide a solution.


### Provide verbose output that clearly demonstrates the problem

- [X] Run **your** yt-dlp command with **-vU** flag added (`yt-dlp -vU <your command line>`)
- [ ] If using API, add `'verbose': True` to `YoutubeDL` params instead
- [X] Copy the WHOLE output (starting with `[debug] Command-line config`) and insert it below

### Complete Verbose Output

```shell
yt-dlp -vU https://anamihalceamdphd.substack.com/p/video-of-c19-pfizer-bioweapon-shows                                                          ✱
[debug] Command-line config: ['-vU', 'https://anamihalceamdphd.substack.com/p/video-of-c19-pfizer-bioweapon-shows']
[debug] Encodings: locale UTF-8, fs utf-8, pref UTF-8, out utf-8, error utf-8, screen utf-8
[debug] yt-dlp version stable@2023.07.06 [b532a3481]
[debug] Lazy loading extractors is disabled
[debug] Python 3.11.4 (CPython x86_64 64bit) - macOS-12.6.8-x86_64-i386-64bit (OpenSSL 3.1.1 30 May 2023)
[debug] exe versions: ffmpeg 6.0 (setts), ffprobe 6.0, phantomjs 2.1.1, rtmpdump 2.4
[debug] Optional libraries: Cryptodome-3.18.0, brotli-1.0.9, certifi-2023.07.22, mutagen-1.46.0, sqlite3-2.6.0, websockets-11.0.3
[debug] Proxy map: {}
[debug] Loaded 1864 extractors
[debug] Fetching release info: https://api.github.com/repos/yt-dlp/yt-dlp/releases/latest
Available version: stable@2023.07.06, Current version: stable@2023.07.06
yt-dlp is up to date (stable@2023.07.06)
[Substack] Extracting URL: https://anamihalceamdphd.substack.com/p/video-of-c19-pfizer-bioweapon-shows
[Substack] video-of-c19-pfizer-bioweapon-shows: Downloading webpage
ERROR: [Substack] video-of-c19-pfizer-bioweapon-shows: Page type "newsletter" is not supported; please report this issue on  https://github.com/yt-dlp/yt-dlp/issues?q= , filling out the appropriate issue template. Confirm you are on the latest version using  yt-dlp -U
  File "/usr/local/lib/python3.11/site-packages/yt_dlp/extractor/common.py", line 715, in extract
    ie_result = self._real_extract(url)
                ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/yt_dlp/extractor/substack.py", line 91, in _real_extract
    self.raise_no_formats(f'Page type "{post_type}" is not supported')
  File "/usr/local/lib/python3.11/site-packages/yt_dlp/extractor/common.py", line 1193, in raise_no_formats
    raise ExtractorError(msg, expected=expected, video_id=video_id)
```