I've just spent more than an hour debugging a very stupid issue for a user of my Slideshare plugin. Your WordPress Video Plugin doesn't use the internal Shortcode API, but instead uses tons of it's own defines and regexps.
It shows you can code quite well, but it is not exactly the way these things are supposed to be done within a WordPress plugin. I've "fixed" it by doing the following:
// Make sure [slideshare] shortcodes are executed by the correct plugin, by giving the WordPress video plugin an erroneous regexp. define("SS_REGEXP", "/\[ss (<a href="http://codex.wordpress.org/:print:">:print:</a>+)\]/");
But... It'd be nice if you actually used the ShortCode API so I could overwrite your slideshare shortcode with my own...
Thanks for considering it!
Joost de Valk