<?php
$re = '/{youtube}(.*){\/youtube}/mis';
$str = 'Life is good {youtube}NgBZrRCPCH8{/youtube}
Fun is great! {youtube}joRCPCH8{/youtube}
Earth is round and roll\n {youtube}pwnkfH8{/youtube}';
preg_match_all($re, $str, $matches);
print_r($matches);
Array
(
[0] => Array
(
[0] => {youtube}NgBZrRCPCH8{/youtube}
Fun is great! {youtube}joRCPCH8{/youtube}
Earth is round and roll\n {youtube}pwnkfH8{/youtube}
)
[1] => Array
(
[0] => NgBZrRCPCH8{/youtube}
Fun is great! {youtube}joRCPCH8{/youtube}
Earth is round and roll\n {youtube}pwnkfH8
)
)