Repository: yt-dlp
Issue: Site request for plex.tv
Labels: site-request

### Checklist

- [X] I'm reporting a new site support request
- [X] I've verified that I'm running yt-dlp version **2022.05.18** ([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/ytdl-org/youtube-dl#can-you-add-support-for-this-anime-video-site-or-site-which-shows-current-movies-for-free) 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)
- [X] 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

Anywhere

### Example URLs

https://watch.plex.tv/movie/borderline

### Description

For the example URL, click on 'Watch now' to load the video. It may not play unless if you have adblocker disabled. I've taken the URL and entered it yt-dlp with the following verbose log.

I have also tried grabbing any available stream link with the network tab but could not locate any playlist or master .m3u8 links to use. Thanks.
update: there is a .mpd link that includes a token key but not sure how to use it for yt-dlp

### Verbose log

```shell
[debug] Command-line config: ['-vU', 'https://watch.plex.tv/movie/borderline']
[debug] Encodings: locale cp1252, fs utf-8, pref cp1252, out utf-8, error utf-8, screen utf-8
[debug] yt-dlp version 2022.05.18 [b14d523] (win_exe)
[debug] Python version 3.8.10 (CPython 64bit) - Windows-10-10.0.19043-SP0
[debug] Checking exe version: ffprobe -bsfs
[debug] Checking exe version: avprobe -bsfs
[debug] Checking exe version: ffmpeg -bsfs
[debug] exe versions: ffmpeg 4.4.1-essentials_build-www.gyan.dev (setts)
[debug] Optional libraries: Cryptodome-3.14.1, brotli-1.0.9, certifi-2021.10.08, mutagen-1.45.1, sqlite3-2.6.0, websockets-10.3
[debug] Proxy map: {}
Latest version: 2022.05.18, Current version: 2022.05.18
yt-dlp is up to date (2022.05.18)
[debug] [generic] Extracting URL: https://watch.plex.tv/movie/borderline
[generic] borderline: Requesting header
WARNING: [generic] Falling back on generic information extractor.
[generic] borderline: Downloading webpage
[generic] borderline: Extracting information
[debug] Looking for video embeds
[debug] Identified a HTML5 media
[debug] Formats sorted by: hasvid, ie_pref, lang, quality, res, fps, hdr:12(7), vcodec:vp9.2(10), acodec, filesize, fs_approx, tbr, vbr, abr, asr, proto, vext, aext, hasaud, source, id
[download] Downloading playlist: Borderline (1980)
[generic] playlist Borderline (1980): Collected 1 videos; downloading 1 of them
[download] Downloading video 1 of 1
[debug] Default format spec: bestvideo*+bestaudio/best
[info] borderline: Downloading 1 format(s): 0
[debug] Invoking http downloader on "https://watch.plex.tv/auto-play-sample.mp4"
[debug] File locking is not supported on this platform. Proceeding without locking
[download] Destination: Borderline (1980) [borderline].mp4
[download] 100% of 1.46KiB in 00:00
[download] Finished downloading playlist: Borderline (1980)
```