$re = '/((?:[A-Za-z]+-?)*)-in-((?:[A-Za-z]+-?)*)(?:\.[\w]{3,4})?/m';
$str = 'Sammi-Tye-in-Beauty.mp4
Sammi-Tye-in-Classic-Curves.mp4
Sammi-Tye-in-Classy-Erotica.mp4
Sammi-Tye-in-Classy-Erotica';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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