This would be cool I think, there is an issue with having swf in databases though I believe.
on my test board, i did a bit of modification such that when attachment display images is enabled it will open the swf movie attached in the thread.
example:
http://66.78.33.178/forum/showthread.php?threadid=1833
Now it does show, however as it is loaded from the mysql, it does not know the width and height of the flash, and as such it defaults to a certain size, i believe this is something to do with the plugin, as i was told by a user that on Mac the attached flash defaults to 5x5, or 50x50 .. one of those..