[mixcloud] Fix extraction (closes #13958)

youtube_dl/extractor/mixcloud.py

@@ -91,9 +91,11 @@ class MixcloudIE(InfoExtractor):
             if js_url:
                 js = self._download_webpage(js_url, track_id, fatal=False)
                 if js:
+                    KEY_RE_TEMPLATE = r'player\s*:\s*{.*?\b%s\s*:\s*(["\'])(?P<key>(?:(?!\1).)+)\1'
+                    for key_name in ('value', 'key_value'):
                         key = self._search_regex(
-                        r'player\s*:\s*{.*?\bvalue\s*:\s*(["\'])(?P<key>(?:(?!\1).)+)\1',
-                        js, 'key', default=None, group='key')
+                            KEY_RE_TEMPLATE % key_name, js, 'key',
+                            default=None, group='key')
                         if key and isinstance(key, compat_str):
                             self._keys.insert(0, key)
                             self._current_key = key