$re = '/^https?:\/\/flyheight.com\/videos\/[a-z0-9]{6}$/m';
$str = 'https://flyheight.com/videos/ybb347
https://flyheight.com/videos/yb24os
https://flyheight.com/public/images/videos/793f77362f321e62c32659c3ab00952d.png
https://flyheight.com/videos/5o6t98/#disqus_thread';
preg_match_all($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