- var_dump: documentation ( source)
- preg_match: documentation ( source)
<?php
$_content = '<p class="post_content">[iframe width="256" height="175" src="http://www.youtube.com/embed/ICx3AfSlc-w" frameborder="0" allowfullscreen]</p>
<div class="post_source_linkbar">
<img class="post_source_logo" src="http://economyincrisis.org/wp-content/uploads/2011/08/EICtext5.png"><img class="post_source_icon" title="Economy In Crisis" src="http://www.google.com/s2/favicons?domain=http%3A%2F%2Feconomyincrisis.org%2F">Source</div>';
preg_match('/https?:\/\/(?:[0-9A-Z-]+\.)?(?:youtu\.be\/|youtube\.com(?:\/embed\/|\/v\/|\/watch\?v=|\/ytscreeningroom\?v=|\/feeds\/api\/videos\/|\/user\S*[^\w\-\s]|\S*[^\w\-\s]))([\w\-]{11})[?=&+%\w-]*/i', $_content, $media);
var_dump($media);