-        sources_raw = self._search_regex(
-            r'(?s)sources:\s*(\[.*?\]),', webpage, 'video URLs', default=None)
-        if sources_raw is None:
-            alt_source = self._search_regex(
-                r'(file: ".*?"),', webpage, 'video URL', default=None)
-            if alt_source:
-                sources_raw = '[{ %s}]' % alt_source
-            else:
-                # Maybe an embed?
-                embed_url = self._search_regex(
-                    r'<iframe[^>]+src="(http://www.prochan.com/embed\?[^"]+)"',
-                    webpage, 'embed URL')
-                return {
-                    '_type': 'url_transparent',
-                    'url': embed_url,
-                    'id': video_id,
-                    'title': video_title,
-                    'description': video_description,
-                    'uploader': video_uploader,
-                    'age_limit': age_limit,
-                }