[xtube] Fix typo

youtube_dl/extractor/xtube.py

@@ -100,7 +100,7 @@ class XTubeIE(InfoExtractor):
                 duration = int_or_none(config.get('duration'))
                 sources = config.get('sources') or config.get('format')
 
-        if isinstance(sources, dict):
+        if not isinstance(sources, dict):
             sources = self._parse_json(self._search_regex(
                 r'(["\'])?sources\1?\s*:\s*(?P<sources>{.+?}),',
                 webpage, 'sources', group='sources'), video_id,