Index: src/wp-includes/media.php
===================================================================
--- src/wp-includes/media.php	(revision 31016)
+++ src/wp-includes/media.php	(working copy)
@@ -2293,9 +2293,9 @@
 }
 
 /**
- * YouTube embed handler callback.
+ * YouTube iframe embed handler callback.
  *
- * Catches URLs that can be parsed but aren't supported by oEmbed.
+ * Catches YouTube iframe embed URLs that are not parsable by oEmbed but can be translated into a URL that is.
  *
  * @since 4.0.0
  *