youtube bbcode help

[UnknownPlayer]

I have this function:

    function bbcode($input){
        $input = strip_tags($input);
        $input = htmlentities($input);
        
        $search = array(
                    '/\[b\](.*?)\[\/b\]/is',
                    '/\[i\](.*?)\[\/i\]/is',
                    '/\[u\](.*?)\[\/u\]/is',
                    '/\[img\](.*?)\[\/img\]/is',
                    '/\[url=http://(.*?)\](.*?)\[\/url\]/is',
                    '/\[color=(.*?)\](.*?)\[\/color\]/is',
                    '/\[yt\](.*?)\[\/yt\]/is',
        );
        
        $replace = array(
                    '<b>$1</b>',
                    '<i>$1</i>',
                    '<u>$1</u>',
                    '<img src="$1" style="border:0">',
                    '<a href="$1">$2</a>',
                    '<font style="color:$1">$2</font>',
                    '<object width="660" height="405">
                    <param name="movie" value="'.str_replace("watch?v=", "v/", $1).'" />
                    <param name="allowFullScreen" value="true" />
                    <param name="allowscriptaccess" value="always" /><embed type="application/x-shockwave-flash" width="660" height="405" src="'.str_replace("watch?v=", "v/", $1).'" allowscriptaccess="always" allowfullscreen="true"></embed>
                    </object>',
        );
        
        return nl2br(preg_replace($search,$replace,$input));
    }

There is an error on code:

<param name="movie" value="'.str_replace("watch?v=", "v/", $1).'" />

and on:

<param name="allowscriptaccess" value="always" /><embed type="application/x-shockwave-flash" width="660" height="405" src="'.str_replace("watch?v=", "v/", $1).'" allowscriptaccess="always" allowfullscreen="true">

How can i use str_replace in this situation ? :S

[jcbones]

According to the manual, use the 'e' modifier on your [yt] search pattern. 

[UnknownPlayer]

Can you write me code ?

I need to put str_replace("watch?v=", "v/", $1) in this array, and i dont know how to do that?