I see a problem; I don't know if it's the same issue: In Safari 2.0.3, the thumbs load fine, but clicking on an image shows multiple progress bars, and then an image. Activity shows 'plug-in cancelled' (Window --> Activity). 'Advertising' doesn't work for me sometimes (no progress bar). The only thing that would explain this is either a variable is getting rewritten (a global) and overriding the loader code, or it's also tweaking paths to .swfs. My guess, without knowing much about your file, and not knowing a lot of AS. Looking at your development site, my guess is it could be a path (code) or permissions (server) issue perhaps? I know that it's been painful to address paths sometimes with Flash (e.g., a SWF lives in a folder, that's embedded two levels up, that addresses a SWF two levels down, etc.)
HTH