Although I tend to stay away from flash there are times when you may want to use it in your site. According to Adobe the proper way to embed a flash object in an HTML document is,
<OBJECT classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000"
codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,40,0"
WIDTH="550" HEIGHT="400" id="myMovieName"><PARAM NAME=movie VALUE="myFlashMovie.swf"><PARAM NAME=quality VALUE=high><PARAM NAME=bgcolor VALUE=#FFFFFF><EMBED src="myFlashMovie.swf" quality=high bgcolor=#FFFFFF WIDTH="550" HEIGHT="400"
NAME="myMovieName" ALIGN="" TYPE="application/x-shockwave-flash"
PLUGINSPAGE="http://www.macromedia.com/go/getflashplayer"></EMBED></OBJECT>
The problem with this is it’s not XHTML valid. The embed tag is something invented by Netscape and never was a part of the W3C specs. Fortunately there is a way to properly embed flash so that it does validate,
<object type="application/x-shockwave-flash" data="myFlashMovie.swf" height="400" width="550"><param name="movie" value="myFlashMovie.swf" /></object>
Isn’t that much nicer? Alternatively you may wish to use a plugin for your WordPress site. The Kimili Flash Embed plugin will automagically embed valid flash objects in your document via the use of its special tag,
[kml_flashembed movie="/path/to/your/movie.swf" height="300" width="300" /]

Thanks, dude! I’ve been looking for something nice ‘n’ simple like this for a while but never quite got around to it…
You’re most welcome Dennis.
It doesn’t work in FireFox
Thanks for the input Steve. I haven’t actually tested it using Firefox.
My friend and I were frustrated by this problem, and we saw a lot of other people were too, so we released a free tool called Validifier. Hope this helps someone! Check it out at http://validifier.com/
Thanks for the heads up Nick!