Index: wp-includes/media.php
===================================================================
--- wp-includes/media.php	(revision 15489)
+++ wp-includes/media.php	(working copy)
@@ -1156,6 +1156,10 @@
 		$rawattr = $attr;
 		$attr = wp_parse_args( $attr, wp_embed_defaults() );
 
+		// kses converts & into & and we need to undo this
+		// See http://core.trac.wordpress.org/ticket/11311
+		$url = str_replace( '&', '&', $url );
+
 		// Look for known internal handlers
 		ksort( $this->handlers );
 		foreach ( $this->handlers as $priority => $handlers ) {