WordPress at a glance
action is not described

enqueue_embed_scripts action-hook . WP 4.4.0

Fires when scripts and styles are enqueued for the embed iframe.

Usage

add_action( 'enqueue_embed_scripts', 'action_function_name_4277' );
function action_function_name_4277(){
	// action...
}

Where the hook is called

enqueue_embed_scripts()
wp-includes/embed.php 929
do_action( 'enqueue_embed_scripts' );

Where the hook is used (in WP core)

Does not used.