Posts should contain text and minimal html only. That’s sort of the whole point of keeping them separated from the rest of the blog. Every time you stray from that, you make your life harder and erode the separation of the blog and the content of the blog a little further. If you change your theme, will your posts suddenly not work anymore? Something to consider, you know?
Thank you Otto, yes, that you say makes sense, blogs are usually for posting text and minimal html and what I usually use is flash, video, flv, etc, that makes things complicated so I need plugins and staff. I will look at your link now.