WordPress MU

I used code bellow (kses.php) as a plugin placed inside MU-plugins dir. It woked fine until I did an upgrade from MU 1.3.3 to MU 1.5 release candidate. What could cause this strange behavior?

<?php

function addabitofclass( $tags ) {
    global $allowedposttags;
    foreach( $allowedposttags as $tag => $attr ) {
        $attr[ 'class' ] = array();
        $attr[ 'id' ] = array();
        $allowedposttags[ $tag ] = $attr;
    }
    return $allowedposttags;
}
add_filter( 'edit_allowedposttags', 'addabitofclass' );
?>

please write how work this plugin until wp mu upgrade, and what happens now (any error code or something...)

It allowed me to add classes and ids to posts. Anyway I think I managed to solve my problem using this plugin: http://wpmudevorg.wordpress.com/project/Allow-Embedded-Videos

My question is: Is the right way to do it? In the long run.

Donncha?

That should have worked, but it's probably not needed now as id and class have been added to many html tags.

Thanks