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<?php $string = '<iframe width="640" height="360" src="http://www.youtube.com/embed/h9jOaIB1VGo?rel=0&wmode=transparent" frameborder="0" allowfullscreen></iframe>'; preg_match('/(youtu\.be\/|youtube\.com\/(watch\?(.*&)?v=|(embed|v)\/))([^\?&"\'>]+)/', $string, $matches); var_dump(key($matches));

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