[vine] Provide alt_title (Fixes #4448)

youtube_dl/extractor/common.py

@@ -118,6 +118,7 @@ class InfoExtractor(object):
 
     The following fields are optional:
 
+    alt_title:      A secondary title of the video.
     display_id      An alternative identifier for the video, not necessarily
                     unique, but available before title. Typically, id is
                     something like "4234987", title "Dancing naked mole rats",
@@ -129,7 +130,7 @@ class InfoExtractor(object):
                         * "resolution" (optional, string "{width}x{height"},
                                         deprecated)
     thumbnail:      Full URL to a video thumbnail image.
-    description:    One-line video description.
+    description:    Full video description.
     uploader:       Full name of the video uploader.
     timestamp:      UNIX timestamp of the moment the video became available.
     upload_date:    Video upload date (YYYYMMDD).

youtube_dl/extractor/vine.py

@@ -17,6 +17,7 @@ class VineIE(InfoExtractor):
             'id': 'b9KOOWX7HUx',
             'ext': 'mp4',
             'title': 'Chicken.',
+            'alt_title': 'Vine by Jack Dorsey',
             'description': 'Chicken.',
             'upload_date': '20130519',
             'uploader': 'Jack Dorsey',
@@ -44,6 +45,7 @@ class VineIE(InfoExtractor):
         return {
             'id': video_id,
             'title': self._og_search_title(webpage),
+            'alt_title': self._og_search_description(webpage),
             'description': data['description'],
             'thumbnail': data['thumbnailUrl'],
             'upload_date': unified_strdate(data['created']),