Hello,
I have a page that have toolbar at top and an iframe below the toolbar. It is Stumbleupon style. Some web pages that are loading into iframe has flash objects and those open on my modal div. How can I hide flash objects in iframe? You may see it in action here: http://www.yemeklog.com/1-pakistana-yardim-zamani.html Please click on "Yorum" text on toolbar.
You cannot modify the page content from pages that are on other domains. It is called the same origin policy.
As mentioned here already, you cannot modify the pages when they're on other domains.
However, you can solve your problem by placing an iframe behind the modal div. More info and an example (non jquery) you can find here: http://www.ozzu.com/website-design-forum/placing-div-over-flash-iframe-t94789.html