Index: wp-includes/class-oembed.php
===================================================================
--- wp-includes/class-oembed.php	(revision 26810)
+++ wp-includes/class-oembed.php	(working copy)
@@ -27,8 +27,8 @@
 	 */
 	function __construct() {
 		$providers = array(
-			'#https?://(www\.)?youtube\.com/watch.*#i'           => array( 'http://www.youtube.com/oembed',                     true  ),
-			'http://youtu.be/*'                                  => array( 'http://www.youtube.com/oembed',                     false ),
+			'#https?://(www\.)?youtube\.com/watch.*#i'           => array( 'http://www.youtube.com/oembed?scheme=https',        true  ),
+			'#https?://youtu\.be/.*#i'                           => array( 'http://www.youtube.com/oembed?scheme=https',        true  ),
 			'http://blip.tv/*'                                   => array( 'http://blip.tv/oembed/',                            false ),
 			'#https?://(www\.)?vimeo\.com/.*#i'                  => array( 'http://vimeo.com/api/oembed.{format}',              true  ),
 			'#https?://(www\.)?dailymotion\.com/.*#i'            => array( 'http://www.dailymotion.com/services/oembed',        true  ),