$re = '/img data-original="([^"]*)"/';
$str = '<img data-original="http://www.video.mediaset.it/bin/515.$plit/640x360_C_2_video_773293_videoThumbnail.jpg" alt="I vincitori di Maria Express" class="img-responsive lazy" width="323" height="186">';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php