[brightcove] add another method to extract policyKey

youtube_dl/extractor/brightcove.py

@@ -28,6 +28,7 @@ from ..utils import (
     parse_iso8601,
     smuggle_url,
     str_or_none,
+    try_get,
     unescapeHTML,
     unsmuggle_url,
     UnsupportedError,
@@ -600,11 +601,14 @@ class BrightcoveNewIE(AdobePassIE):
         store_pk = lambda x: self._downloader.cache.store('brightcove', policy_key_id, x)
 
         def extract_policy_key():
+            base_url = 'http://players.brightcove.net/%s/%s_%s/' % (account_id, player_id, embed)
+            config = self._download_json(
+                base_url + 'config.json', video_id, fatal=False) or {}
+            policy_key = try_get(
+                config, lambda x: x['video_cloud']['policy_key'])
+            if not policy_key:
                 webpage = self._download_webpage(
-                'http://players.brightcove.net/%s/%s_%s/index.min.js'
-                % (account_id, player_id, embed), video_id)
-
-            policy_key = None
+                    base_url + 'index.min.js', video_id)
 
                 catalog = self._search_regex(
                     r'catalog\(({.+?})\);', webpage, 'catalog', default=None)