Youtube looper

looper.php

<?php

if (isset($_POST['video_req']) && ! empty($_POST['video_req'])){
	if ( preg_match("+youtube.com+", $_POST['video_req']) ) {
		$video = htmlspecialchars($_POST['video_req']);
		$strpos_yt = strpos($video, "youtube.com");
		$beginning = substr($video, 0, $strpos_yt) ;

		if ($beginning != "http://www." ) 
		{$video = substr_replace ($video, "http://www.", 0, $strpos_yt ) ;}
		
		if (substr_count($video, "watch?v=") >0 )
			{$video = str_replace('watch?v=', 'embed/', $video) ;}
			
		$end = strpos($video, "embed/");
		$video_id = substr($video, $end + 6);
		$video .= "?enablejsapi=1&version=3&autoplay=1&loop=1&playlist=" 
			. $video_id;

		echo '<iframe width="560" height="315" src="' . $video . 
		'" frameborder="0" allowfullscreen></iframe>';
		
	} else
		{echo "Please enter a valid youtube url.";}
}
?>