Removed sleep and sleep output when interval is zero

youtube_dl/downloader/common.py

@@ -279,6 +279,7 @@ class FileDownloader(object):
         Return True on success and False otherwise
         """
         sleep_interval = self.params.get('sleepinterval', 0)
+        if sleep_interval > 0:
             self.to_screen(u'[download] Sleeping %d seconds...' %sleep_interval)
             time.sleep(sleep_interval)
         # Check file already present