$re = '/yt(?<ytVer>[a-z])(?<ytID>[a-zA-Z0-9-_]{8,11})/m';
$str = 'https://www.youtube.com/watch?v=f7dWJcJgEjE?list
https://youtu.be/voceyAq-R9E
https://www.youtube.com/embed/f7dWJcJgEjE
https://youtu.be/watch?v=DKbQFMOEFTs
ytaDKbQFMOEFTs
ytzvoceyAq-R9E
';
preg_match_all($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