There is a problem with IE (might occur on other browsers as well) when html element used to handle directive is hidden initially (or contains visibility logic).
It is well described for example here:
http://www.plupload.com/punbb/viewtopic.php?id=3918
It would be nice to have access to some methods of uploader like refresh in this case, or generally to uploader object itself.
BTW: nice and useful directive.