Bonjour bastien,
Voici une solution:
PHP Code:
$text = '<div><object width="425" height="255"><param name="movie" value="http://www.dailymotion.com/swf/5XfKpEkBU9Ry1kuwQ"></param><param name="allowfullscreen" value="true"></param><embed src="http://www.dailymotion.com/swf/5XfKpEkBU9Ry1kuwQ" type="application/x-shockwave-flash" width="425" height="255" allowfullscreen="true"></embed></object><br /><b><a href="http://www.dailymotion.com/video/x2wogc_halo-3-combat_creation">Halo 3 combat</a></b><br /><i>envoyé par <a href="http://www.dailymotion.com/xbox">xbox</a></i></div>';
preg_match(\"#<param name=\\\"movie\\\" value=\\\"http://www.dailymotion.com/swf/(.+?)\\\"></param>#\", $text, $matches);
echo $matches[1];