From ee61f6f3e2f4d03a3ad9c5ca8f4fc5cd9461bdbc Mon Sep 17 00:00:00 2001
From: Philipp Hagemeister <phihag@phihag.de>
Date: Mon, 5 Jan 2015 22:42:17 +0100
Subject: [PATCH] [youtube] Handle cases where format comes without a
 preference (Fixes #4648)

---
 youtube_dl/extractor/youtube.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/youtube_dl/extractor/youtube.py b/youtube_dl/extractor/youtube.py
index d1bbf0b01..4aa8615b4 100644
--- a/youtube_dl/extractor/youtube.py
+++ b/youtube_dl/extractor/youtube.py
@@ -1046,7 +1046,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor, SubtitlesInfoExtractor):
                     for f in formats:
                         if f['format_id'] in dash_keys:
                             f['format_id'] = 'nondash-%s' % f['format_id']
-                            f['preference'] -= 10000
+                            f['preference'] = f.get('preference', 0) - 10000
                     formats.extend(dash_formats)
 
         self._sort_formats(formats)