[downloader/external] Simplify

youtube_dl/downloader/external.py

@@ -47,7 +47,7 @@ class ExternalFD(FileDownloader):
 
     def _source_address(self, command_option):
         command_part = []
-        source_address = self.ydl.params.get('source_address')
+        source_address = self.params.get('source_address')
         if source_address:
             command_part = [command_option, source_address]
         return command_part