--- home/jonne/Desktop/video_filter/video_filter.codecs.inc 
+++ var/www/xxx/modules/video_filter/video_filter.codecs.inc 
@@ -8,7 +8,7 @@
 	$codecs['youtube'] = array(
 		'name' => t('YouTube'),
 		'callback' => 'video_filter_youtube',
-		'regexp' => '/youtube\.com\/watch\?v=([a-z0-9]+)/i',
+		'regexp' => '/youtube\.com\/watch\?v=([a-z0-9_]+)/i',
 		'ratio' => 425 / 355,
 	);
 	$codecs['google'] = array(