Repository: yt-dlp/yt-dlp

Issue:
Steam Live Stream
### 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

Canada

### Example URLs

https://steamcommunity.com/broadcast/watch/76561198373527746

### Description

Hello, 

Could you please add support for Steam live streams?

Please note that the provided content at this URL: https://steamcommunity.com/broadcast/watch/76561198373527746 is a live stream and will probably not available for an undefined period of time. 

I'd look on the Issues section and Pull Requests and I wasn't able to find anything. 

Best regards, 

Guillaume

### Verbose log

```shell
root@livestream-dc:/mnt/disk/livestream# yt-dlp https://steamcommunity.com/broadcast/watch/76561198373527746
[generic] 76561198373527746: Requesting header
WARNING: [generic] Could not send HEAD request to https://steamcommunity.com/broadcast/watch/76561198373527746: HTTP Error 503: Service Unavailable
[generic] 76561198373527746: Downloading webpage
WARNING: [generic] Falling back on generic information extractor.
[generic] 76561198373527746: Extracting information
ERROR: Unsupported URL: https://steamcommunity.com/broadcast/watch/76561198373527746
root@livestream-dc:/mnt/disk/livestream#
```



Discussion:

Resolving patch:
diff --git a/yt_dlp/extractor/_extractors.py b/yt_dlp/extractor/_extractors.py
--- a/yt_dlp/extractor/_extractors.py
+++ b/yt_dlp/extractor/_extractors.py
@@ -1630,7 +1630,10 @@
 from .srmediathek import SRMediathekIE
 from .stanfordoc import StanfordOpenClassroomIE
 from .startv import StarTVIE
-from .steam import SteamIE
+from .steam import (
+    SteamIE,
+    SteamCommunityBroadcastIE,
+)
 from .storyfire import (
     StoryFireIE,
     StoryFireUserIE,
diff --git a/yt_dlp/extractor/steam.py b/yt_dlp/extractor/steam.py
--- a/yt_dlp/extractor/steam.py
+++ b/yt_dlp/extractor/steam.py
@@ -127,3 +127,50 @@ def _real_extract(self, url):
             raise ExtractorError('Could not find any videos')
 
         return self.playlist_result(entries, playlist_id, playlist_title)
+
+
+class SteamCommunityBroadcastIE(InfoExtractor):
+    _VALID_URL = r'https?://steamcommunity\.(?:com)/broadcast/watch/(?P<id>\d+)'
+    _TESTS = [{
+        'url': 'https://steamcommunity.com/broadcast/watch/76561199073851486',
+        'info_dict': {
+            'id': '76561199073851486',
+            'title': r're:Steam Community :: pepperm!nt :: Broadcast 2022-06-26 \d{2}:\d{2}',
+            'ext': 'mp4',
+            'uploader_id': 1113585758,
+            'uploader': 'pepperm!nt',
+            'live_status': 'is_live',
+        },
+        'skip': 'Stream has ended',
+    }]
+
+    def _real_extract(self, url):
+        video_id = self._match_id(url)
+        webpage = self._download_webpage(url, video_id)
+        json_data = self._download_json(
+            'https://steamcommunity.com/broadcast/getbroadcastmpd/',
+            video_id, query={'steamid': f'{video_id}'})
+
+        formats, subs = self._extract_m3u8_formats_and_subtitles(json_data['hls_url'], video_id)
+
+        ''' # We cannot download live dash atm
+        mpd_formats, mpd_subs = self._extract_mpd_formats_and_subtitles(json_data['url'], video_id)
+        formats.extend(mpd_formats)
+        self._merge_subtitles(mpd_subs, target=subs)
+        '''
+
+        uploader_json = self._download_json(
+            'https://steamcommunity.com/actions/ajaxresolveusers',
+            video_id, query={'steamids': video_id})[0]
+
+        self._sort_formats(formats)
+        return {
+            'id': video_id,
+            'title': self._html_extract_title(webpage) or self._og_search_title(webpage),
+            'formats': formats,
+            'live_status': 'is_live',
+            'view_count': json_data.get('num_view'),
+            'uploader': uploader_json.get('persona_name'),
+            'uploader_id': uploader_json.get('accountid'),
+            'subtitles': subs,
+        }


Test patch: