$re = '/:[^()]+?![^()]+?.tmi.twitch.tv PRIVMSG #[^()]+? :[^()]+?\\\\r\\\\n/m';
$str = ':hey!hey.tmi.twitch.tv PRIVMSG #stream :message here\\r\\n:otherhey!otherhey!tmi.twitch.tv PRIVMSG #otherstream :othermessage here\\r\\n';
preg_match_all($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