PLEASE HELP GIMP-GAP

Gap doesn't support Swf
You may use "Video/split animation into frames" to get a series of png, and one of the many free utilities around to convert the png into swf

Or see the sticky on the plugin board of www.gimptalk.com for a python plugin to export in swf directly from Gimp

BUT note the plugin will fail if the path for save has embedded spaces (as in windows any subfolder of "Documents and Settings", and that include the Video, Document, and Image folders

And in Windows support for Python plugin as default is not enabled...so you may prefer the first solution