[youtube] Add support for multifeed videos
diff --git a/youtube_dl/extractor/youtube.py b/youtube_dl/extractor/youtube.py
index 4023a6e50ba..8a5ef2e7028 100644
--- a/youtube_dl/extractor/youtube.py
+++ b/youtube_dl/extractor/youtube.py
@@ -33,9 +33,11 @@
     int_or_none,
     orderedSet,
     parse_duration,
+    smuggle_url,
     str_to_int,
     unescapeHTML,
     unified_strdate,
+    unsmuggle_url,
     uppercase_escape,
     ISO3166Utils,
 )
@@ -558,6 +560,59 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                 'format': '135',  # bestvideo
             }
         },
+        {
+            # Multifeed videos (multiple cameras), URL is for Main Camera
+            'url': 'https://www.youtube.com/watch?v=jqWvoWXjCVs',
+            'info_dict': {
+                'id': 'jqWvoWXjCVs',
+                'title': 'teamPGP: Rocket League Noob Stream',
+                'description': 'md5:dc7872fb300e143831327f1bae3af010',
+            },
+            'playlist': [{
+                'info_dict': {
+                    'id': 'jqWvoWXjCVs',
+                    'ext': 'mp4',
+                    'title': 'teamPGP: Rocket League Noob Stream (Main Camera)',
+                    'description': 'md5:dc7872fb300e143831327f1bae3af010',
+                    'upload_date': '20150721',
+                    'uploader': 'Beer Games Beer',
+                    'uploader_id': 'beergamesbeer',
+                },
+            }, {
+                'info_dict': {
+                    'id': '6h8e8xoXJzg',
+                    'ext': 'mp4',
+                    'title': 'teamPGP: Rocket League Noob Stream (kreestuh)',
+                    'description': 'md5:dc7872fb300e143831327f1bae3af010',
+                    'upload_date': '20150721',
+                    'uploader': 'Beer Games Beer',
+                    'uploader_id': 'beergamesbeer',
+                },
+            }, {
+                'info_dict': {
+                    'id': 'PUOgX5z9xZw',
+                    'ext': 'mp4',
+                    'title': 'teamPGP: Rocket League Noob Stream (grizzle)',
+                    'description': 'md5:dc7872fb300e143831327f1bae3af010',
+                    'upload_date': '20150721',
+                    'uploader': 'Beer Games Beer',
+                    'uploader_id': 'beergamesbeer',
+                },
+            }, {
+                'info_dict': {
+                    'id': 'teuwxikvS5k',
+                    'ext': 'mp4',
+                    'title': 'teamPGP: Rocket League Noob Stream (zim)',
+                    'description': 'md5:dc7872fb300e143831327f1bae3af010',
+                    'upload_date': '20150721',
+                    'uploader': 'Beer Games Beer',
+                    'uploader_id': 'beergamesbeer',
+                },
+            }],
+            'params': {
+                'skip_download': True,
+            },
+        }
     ]
 
     def __init__(self, *args, **kwargs):
@@ -889,6 +944,8 @@ def decrypt_sig(mobj):
         return formats
 
     def _real_extract(self, url):
+        url, smuggled_data = unsmuggle_url(url, {})
+
         proto = (
             'http' if self._downloader.params.get('prefer_insecure', False)
             else 'https')
@@ -1005,6 +1062,55 @@ def add_dash_mpd(video_info):
                     '"token" parameter not in video info for unknown reason',
                     video_id=video_id)
 
+        # title
+        if 'title' in video_info:
+            video_title = video_info['title'][0]
+        else:
+            self._downloader.report_warning('Unable to extract video title')
+            video_title = '_'
+
+        # description
+        video_description = get_element_by_id("eow-description", video_webpage)
+        if video_description:
+            video_description = re.sub(r'''(?x)
+                <a\s+
+                    (?:[a-zA-Z-]+="[^"]+"\s+)*?
+                    title="([^"]+)"\s+
+                    (?:[a-zA-Z-]+="[^"]+"\s+)*?
+                    class="yt-uix-redirect-link"\s*>
+                [^<]+
+                </a>
+            ''', r'\1', video_description)
+            video_description = clean_html(video_description)
+        else:
+            fd_mobj = re.search(r'<meta name="description" content="([^"]+)"', video_webpage)
+            if fd_mobj:
+                video_description = unescapeHTML(fd_mobj.group(1))
+            else:
+                video_description = ''
+
+        if 'multifeed_metadata_list' in video_info and not smuggled_data.get('force_singlefeed', False):
+            if not self._downloader.params.get('noplaylist'):
+                entries = []
+                feed_ids = []
+                multifeed_metadata_list = compat_urllib_parse_unquote_plus(video_info['multifeed_metadata_list'][0])
+                for feed in multifeed_metadata_list.split(','):
+                    feed_data = compat_parse_qs(feed)
+                    entries.append({
+                        '_type': 'url_transparent',
+                        'ie_key': 'Youtube',
+                        'url': smuggle_url(
+                            '%s://www.youtube.com/watch?v=%s' % (proto, feed_data['id'][0]),
+                            {'force_singlefeed': True}),
+                        'title': '%s (%s)' % (video_title, feed_data['title'][0]),
+                    })
+                    feed_ids.append(feed_data['id'][0])
+                self.to_screen(
+                    'Downloading multifeed video (%s) - add --no-playlist to just download video %s'
+                    % (', '.join(feed_ids), video_id))
+                return self.playlist_result(entries, video_id, video_title, video_description)
+            self.to_screen('Downloading just video %s because of --no-playlist' % video_id)
+
         if 'view_count' in video_info:
             view_count = int(video_info['view_count'][0])
         else:
@@ -1030,13 +1136,6 @@ def add_dash_mpd(video_info):
         else:
             self._downloader.report_warning('unable to extract uploader nickname')
 
-        # title
-        if 'title' in video_info:
-            video_title = video_info['title'][0]
-        else:
-            self._downloader.report_warning('Unable to extract video title')
-            video_title = '_'
-
         # thumbnail image
         # We try first to get a high quality image:
         m_thumb = re.search(r'<span itemprop="thumbnail".*?href="(.*?)">',
@@ -1072,26 +1171,6 @@ def add_dash_mpd(video_info):
         else:
             video_categories = None
 
-        # description
-        video_description = get_element_by_id("eow-description", video_webpage)
-        if video_description:
-            video_description = re.sub(r'''(?x)
-                <a\s+
-                    (?:[a-zA-Z-]+="[^"]+"\s+)*?
-                    title="([^"]+)"\s+
-                    (?:[a-zA-Z-]+="[^"]+"\s+)*?
-                    class="yt-uix-redirect-link"\s*>
-                [^<]+
-                </a>
-            ''', r'\1', video_description)
-            video_description = clean_html(video_description)
-        else:
-            fd_mobj = re.search(r'<meta name="description" content="([^"]+)"', video_webpage)
-            if fd_mobj:
-                video_description = unescapeHTML(fd_mobj.group(1))
-            else:
-                video_description = ''
-
         def _extract_count(count_name):
             return str_to_int(self._search_regex(
                 r'-%s-button[^>]+><span[^>]+class="yt-uix-button-content"[^>]*>([\d,]+)</span>'

Adds support for downloading multifeed videos (from multiple cameras) as playlist (e.g. https://www.youtube.com/watch?v=jqWvoWXjCVs)
