Repository: yt-dlp
Issue: soundgasm.net `modified_date` and `modified_timestamp` Not Available
Labels: 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 reporting that yt-dlp is broken on a **supported** site
- [X] I've verified that I have **updated yt-dlp to nightly or master** ([update instructions](https://github.com/yt-dlp/yt-dlp#update-channels))
- [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 all URLs and arguments with special characters are [properly quoted or escaped](https://github.com/yt-dlp/yt-dlp/wiki/FAQ#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 [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)
- [ ] 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

_No response_

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

%(upload_date)s-%(modified_date)s-%(modified_timestamp)s-%(title)s-%(id)s.%(ext)s'

I was gonna post a question asking how to get yt-dlp to fallback to `modified_date` when `upload_date` is `NA` but it turns out that yt-dlp isn't picking up the remote time of file.

    $ curl -s -I -R --location-trusted "$(yt-dlp --no-config https://soundgasm.net/u/Alea_iacta_est_irA/F-DSP-Verification-Request -g)" | grep 'last-modified'
    last-modified: Wed, 13 Apr 2022 21:32:44 GMT

`modified_date` should show up as  `20220413`


### 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
[debug] Command-line config: ['--no-config', '-wv', '--no-cache-dir', '--geo-bypass', '-o', '%(uploader)s-%(upload_date)s-%(modified_date)s-%(modified_timestamp)s-%(title)s-%(id)s.%(ext)s', '--restrict-filenames', 'https://soundgasm.net/u/Alea_iacta_est_irA/F-DSP-Verification-Request']
[debug] yt-dlp version nightly@2024.12.23.232812 from yt-dlp/yt-dlp-nightly-builds [65cf46cdd] (win_exe)
[debug] Python 3.10.11 (CPython AMD64 64bit) - Windows-7-6.1.7601-SP1 (OpenSSL 1.1.1t  7 Feb 2023)
[debug] exe versions: ffmpeg 7.0-full_build-www.gyan.dev (setts), ffprobe 7.0-full_build-www.gyan.dev
[debug] Optional libraries: Cryptodome-3.21.0, brotli-1.1.0, certifi-2024.12.14, curl_cffi-0.5.10, mutagen-1.47.0, requests-2.32.3, sqlite3-3.40.1, urllib3-2.3.0, websockets-14.1
[debug] Request Handlers: urllib, requests, websockets, curl_cffi
[debug] Extractor Plugins: AGB (YoutubeIE), Youtube_AgeGateBypassIE
[debug] Loaded 1838 extractors
[soundgasm] Extracting URL: https://soundgasm.net/u/Alea_iacta_est_irA/F-DSP-Verification-Request
[soundgasm] F-DSP-Verification-Request: Downloading webpage
[debug] Formats sorted by: hasvid, ie_pref, lang, quality, res, fps, hdr:12(7), vcodec, channels, acodec, size, br, asr, proto, vext, aext, hasaud, source, id
[debug] Default format spec: bestvideo*+bestaudio/best
[info] 7150ff8ba1a8c839e6764be01025e52b9101b483: Downloading 1 format(s): 0
[debug] Invoking http downloader on "https://media.soundgasm.net/sounds/7150ff8ba1a8c839e6764be01025e52b9101b483.m4a"
[debug] File locking is not supported. Proceeding without locking
[download] Destination: Alea_iacta_est_irA-NA-NA-NA-F_DSP_Verification_Request-7150ff8ba1a8c839e6764be01025e52b9101b483.m4a
[download] 100% of  664.40KiB in 00:00:02 at 315.01KiB/s
```