PHP Play Random Youtube Video

<html>
<?php
$yt[8] = "IoBP24I2lwA";
$yt[9] = "EhPXdbjGLTc";
$yt[10] = "wlAw48HucqY";
$yt[11] = "uZF9_YndwqY";
$yt[12] = "_zCoCa6b6cU";
$yt[13] = "4GuqB1BQVr4";
$yt[14] = "3mC2ixOAivA";
$yt[15] = "jlrx7tswjxw";
$youtube = rand(8, 15);
?>
<iframe width="560" height="315" src="http://www.youtube.com/embed/<?php echo ($yt[$youtube]); ?>?autoplay=1" frameborder="0" allowfullscreen></iframe>
</html>