$re = '/(?<=,,|::)\h*(?:(?!\S*(?:,,|::))\S+\h+){3}.*?(?=::|,,)/m';
$str = 'test.wav,,200,,This is a test, or is it?::test 2.wav,,test 3.wav::I said: Do not do that,,error.wav';
preg_match_all($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