$re = '/APDNUDES_F20[0-9]{2}_((?:[A-Za-z]+-?)*-in-(?:[A-Za-z]+-?)*)_[P|V][0-9]+(\.[\w]{3,4})?/m';
$str = 'APDNUDES_F2013_Sammi-Tye-in-Beauty_V190522172041.mp4
APDNUDES_F2013_Sammi-Tye-in-Classic-Curves_V190522161615.mp4
APDNUDES_F2013_Sammi-Tye-in-Classy-Erotica_V190522173336.mp4
APDNUDES_F2013_Sammi-Tye-in-Classy-Erotica_V190522173336
';
$subst = "${1}${2}";
$result = preg_replace($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