$re = '/^.*^((?:https?:)?\/\/)?(www\.)?(screencast\.com)(\/users)\/([a-z0-9_-]+)\/folders\/([a-z0-9%_-]+)\/media\/([a-z0-9_-]+)(?:\/)?$/im';
$str = 'https://www.screencast.com/users/arundquist/folders/General%20Physics%20II/media/e2ff7bd7-61ba-4325-b06b-8275e2b94f16
';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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