Código PHP:
<?
if(eregi('youtube.com',$_POST['video'])){
$video="$_POST[video]";
$video2 = explode("watch?v=", $video);
$video2 = explode("&", $video2[1]);
$video2 = $video2[0];
$source = file_get_contents($video);
preg_match("/var fullscreenUrl = '(.*?)';/is", $source, $link);
$link=str_replace('/','',$link[1]);
$link=str_replace("watch_fullscreen?",'',$link);
$title = explode("<title>", $source);
$title = explode("</title>", $title[1]);
$title=str_replace("YouTube - ","",$title[0]);
$pic="http://img.youtube.com/vi/$video2/default.jpg";
echo"<br><b>$title</b><br><br><img src=\"$pic\"><br><br><a href=\"http://www.youtube.com/get_video?$link\">[ DOWNLOAD NOW ]</a>";
}
?>
Desde ya muchas gracias saudos