youtubeid.php

<?php

function yid($url) {
	$pattern = '%^(?:https?://)?(?:www\.)?(?:youtu\.be/|youtube\.com(?:/embed/|/v/|/watch\?v=))([\w-]{10,12})$%x';
	$result = preg_match($pattern, $url, $matches);
	if ($result) {
		return $matches[1];
	}
	return false;
}