I m currently working on the next version of the gallery module. Check this
And i have already implemented the functionality which allows you to load the lightbox content thanks to a ss template.
So the hard work has already been done in order to see other kind of media file in it.
That's why I'm not sure that is useful for u to work on the last version of the lightbox because, it's gonna be easy now to load video files for example and change the content and style of your lightbox.
I think what is gonna be useful from the last version of the lightbox is the new animation at the loading, and also the html code for the videos. But that's it.
It's probably better 4 u not to work on this now, and wait the new gallery module release ( probably middle of August ).