[Plugin: prettyPhoto Media] Doesnt work…unless!

Hiya, before prettyphoto I was using shadowbox.

However, I installed prettyphoto and it doesnt work, so i googled around and found the following in a post.

add_filter('the_content', 'addprettyPhotorel_replace', 12);
add_filter('get_comment_text', 'addprettyPhotorel_replace');
function addprettyPhotorel_replace ($content)
{   global $post;
	$pattern = "/<a(.*?)href=('|\")([^>]*).(bmp|gif|jpeg|jpg|png|avi|mov|mp4|m4v)('|\")(.*?)>(.*?)<\/a>/i";
    $replacement = '<a$1href=$2$3.$4$5 rel="prettyPhoto['.$post->ID.']"$6>$7</a>';
    $content = preg_replace($pattern, $replacement, $content);
    return $content;

I added the above code to my theme’s functions.php and it is now working, why is this?

Do i really need to add that code to my theme’s functions.php?

https://www.ads-software.com/extend/plugins/prettyphoto-media/