diff --git a/youtube_dl/extractor/videolecturesnet.py b/youtube_dl/extractor/videolecturesnet.py
index 1ec5298e9..d46234856 100644
--- a/youtube_dl/extractor/videolecturesnet.py
+++ b/youtube_dl/extractor/videolecturesnet.py
@@ -70,6 +70,7 @@ def _real_extract(self, url):
                 f.update({
                     'url': v.attrib['streamer'],
                     'play_path': src,
+                    'rtmp_real_time': True,
                 })
                 formats.append(f)
         self._sort_formats(formats)