Well, i was programming a page today and wanted to implement BBcode, i found this pack and i found it amazing.
But, i found some wormholes that i filled and i want to share it to improve it

The lines are aprox, cause i changed the code and some lines went a bit lower or upper
First
P: Im a spanish guy, so i do use "á" "é".. charsets, and whenever i used em with the parser it was awful (translated them to a awful code).
S: I had to change htmlentities adding 'UTF-8' , in parser (line ~500) and deparser (line ~905)
Code:
$s = htmlentities($s, ENT_QUOTES,'UTF-8');
$s = html_entity_decode($s, ENT_QUOTES,'UTF-8');
It was a successfull fix, so i suggest to make a way to change the char encoding in a easy way (as a parammeter in p and deparse function)
Second:
P: I was lacking Youtube

S: change parse (~line 573, below font block) deparse(~line 815) (inside the array, at last position)
Code:
$s = preg_replace("#\[youtube\](.*)\[\/youtube\]#Ui", "<object width=\"425\" height=\"350\"><embed src=\"http://www.youtube.com/v/$1\" type=\"application/x-shockwave-flash\" width=\"425\" height=\"350\"></embed></object>", $s);
"[youtube]$1[/youtube]" => "\<object width\=\"425\" height\=\"350\"\>\<embed src\=\"http://www.youtube.com/v/(.*)\" type\=\"application/x-shockwave-flash\" width\=\"425\" height\=\"350\"\>\<\/embed\>\<\/object\>",
);
I added a thir stuff but its my site specific.
pd: I wouldnt care to help you if u need more help

just send me a MP if u want some help.