Avoid browser cache of flash files

To certain date time.
<META http-equiv="expires" content="Mon, 19 Jan 2009 11:34:25 GMT">

Pragma (some browser doesn't support ex. IE5)
<META http-equiv="PRAGMA" content="NO-CACHE">

Query String.
Change link string as a http query string with "?".
<embed src="example.swf?12345">