$re = '/facebook\.com\/(?:photo.php\?v=|video\/embed\?video_id=|v\/?)(\d+)/i';
$str = 'https://www.facebook.com/photo.php?v=0123456789&set=t.674367&type=3&theater
http://www.facebook.com/video/embed?video_id=0123456789
http://www.facebook.com/v/0123456789';
preg_match_all($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