Php osadza wideo z adresu url bez youtube

php dostaje kod do osadzenia z adresu URL z YouTube

preg_replace("/\s*[a-zA-Z\/\/:\.]*youtube.com\/watch\?v=([a-zA-Z0-9\-_]+)([a-zA-Z0-9\/\*\-\_\?\&\;\%\=\.]*)/i","<iframe width=\"420\" height=\"315\" src=\"//www.youtube.com/embed/$1\" frameborder=\"0\" allowfullscreen></iframe>",$post_details['description']);