--- a/src/pyams_media/converter.py	Thu Apr 21 17:01:09 2016 +0200
+++ b/src/pyams_media/converter.py	Thu Apr 21 17:02:16 2016 +0200
@@ -224,6 +224,7 @@
 
     label = _("WebM video converter")
     format = 'webm'
+    require_temp_file = True
 
     def add_common_filters(self, document):
         effects = document.__effects__