when working with swf files (flash animations), there is a nice way to avoid the browser cache. i used to do this by hand, then i used a random number, but with large animations while working online, it gets boring because the server always downloads the whole animation, even if there was no change.
but...
this will do the trick
base.swf?rand=<?php echo filemtime("base.swf") ?>
<embed src="base.swf?rand=<?php echo filemtime("base.swf") ?>" quality="high" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" width="1680" height="1050">