To use Flash in WordPress:
1 Create and test your flash file locally, when you’re done – write down the movie size (Height,Width)
2 Upload your .swf file (make sure you have a good preloader if the file is larger than 50k)
3 At the end of the upload you will get the file link, copy it.
4 Go to the post where you want to insert the flash movie. Put your cursor where you want the movie to appear.
5 In HTML view type this syntax:
Replace “link to/MYFLASHFILE.swf” with the link you copied from step 3.
Replace the ” height=”250″ width=”400” numbers (250 and 400) with the numbers from the first step.
6 Save the post. Click on the movie in the post to run it.
With thanks to Yaniv Steiner (this uses the great Kimili Flash Embed Plugin).
For more information go to the plugin site here