Add BrightcoveIE (closes #832)

It only accepts the urls that are use for embedding the video, it doesn't search in generic webpages to find Brightcove videos

youtube_dl/extractor/brightcove.py

@@ -0,0 +1,32 @@
+import re
+import json
+
+from .common import InfoExtractor
+
+class BrightcoveIE(InfoExtractor):
+    _VALID_URL = r'http://.*brightcove\.com/.*\?(?P<query>.*videoPlayer=(?P<id>\d*).*)'
+
+    def _real_extract(self, url):
+        mobj = re.match(self._VALID_URL, url)
+        query = mobj.group('query')
+        video_id = mobj.group('id')
+
+        request_url = 'http://c.brightcove.com/services/viewer/htmlFederated?%s' % query
+        webpage = self._download_webpage(request_url, video_id)
+
+        self.report_extraction(video_id)
+        info = self._search_regex(r'var experienceJSON = ({.*?});', webpage, 'json')
+        info = json.loads(info)['data']
+        video_info = info['programmedContent']['videoPlayer']['mediaDTO']
+        renditions = video_info['renditions']
+        renditions = sorted(renditions, key=lambda r: r['size'])
+        best_format = renditions[-1]
+        
+        return {'id': video_id,
+                'title': video_info['displayName'],
+                'url': best_format['defaultURL'], 
+                'ext': 'mp4',
+                'description': video_info.get('shortDescription'),
+                'thumbnail': video_info.get('videoStillURL') or video_info.get('thumbnailURL'),
+                'uploader': video_info.get('publisherName'),
+                }