Just a quick reference post for how to embed a YouTube video from a URL string with PHP. The following code includes some extra options to make the player more minimal (less youtubey).
<?php
$url = 'https://www.youtube.com/watch?v=u9-kU7gfuFA';
preg_match('/[\\?\\&]v=([^\\?\\&]+)/', $url, $matches);
$id = $matches[1];
$width = '800px';
$height = '450px';
?>
<iframe id="ytplayer" type="text/html" width="<?php echo $width ?>" height="<?php echo $height ?>"
src="https://www.youtube.com/embed/<?php echo $id ?>?rel=0&showinfo=0&color=white&iv_load_policy=3"
frameborder="0" allowfullscreen></iframe>