[Dismounted]

Originally Posted by Jaxel

Do you mind actually explaining what needs to be done?

You've done a lot of work - and it shows, because you're nearly there. I'm going to give you the rest of it, because unlike a lot of people, you've actually tried doing it yourself.

Hook: bbcode_fetch_tags

PHP Code:

// [VIDEO]
$tag_list['no_option']['video'] = array(
    'callback' => 'handle_external',
    'external_callback' => 'handle_bbcode_video',
    'strip_empty' => true
); 


Hook: bbcode_create

PHP Code:

// include our custom functions
require_once(DIR . '/includes/functions_videodirectory.php');
require_once(DIR . '/includes/class_videosharingservice.php'); 


Function: handle_bbcode_video (/includes/functions_videodirectory.php)

PHP Code:

function handle_bbcode_video(&$parser, $value, $option)
{
        global $vbulletin;

        // clean video id
        $videoid = intval($value);

        // fetch video information -- this is costly, it is run every time the bb code tag is used
        $videoinfo = $vbulletin->db->query_first("
                SELECT *
                FROM " . TABLE_PREFIX . "video
                WHERE video.videoid = " . $videoid . "
                LIMIT 1
        ");

        // check video exists
        if (empty($videoinfo))
        {
                // this will show up on posts -- make sure this is what you want
                return 'This video does not exist.';
        }

        // instantiate our video class
        require_once(DIR . '/includes/videoserviceapi/class_' . strtolower($videoinfo['videoservice']) . '.php');
        $classname = 'vB_VideoSharingService_' . $videoinfo['videoservice'];
        $obj = new $classname($vbulletin);

        // return embed code
        return $obj->fetch_embedcode($videoinfo['videoidservice']);
} 


I've cleaned up and commented the function for you - you should read some of the comments.