I can’t work this out either. I have the imagerotator.swf in the uploads path, as per the notice and documentation, but there is no sign of this ever going to work.
Re: “set the url in the gallery options”, there appears to be only two paths that can be set – the Gallery default path, and the path to imagemagick. Having the SWF in the gallery path doesn’t help, so I assume there is some other secret to this?