WordPress at a glance
action is not described

print_media_templates action-hook . WP 3.5.0

Fires when the custom Backbone media templates are printed.

Usage

add_action( 'print_media_templates', 'action_function_name_714' );
function action_function_name_714(){
	// action...
}

Where the hook is called

wp_print_media_templates()
wp-includes/media-template.php 1270
do_action( 'print_media_templates' );

Where the hook is used (in WP core)

Does not used.