Thanks for the effort. Unfortunately Xmedia-recode won't accept .swf files. I've tried many times, dragging-dropping the .swf files onto the program, but it doesn't accept them. It accepts movie files, such as mp4 and avi etc.
It seems the Format Factory can import swf files. (not 100% sure)
For me, I normally use a software named Moyea SWF to Video Converter.
It's not freeware but provides free trials.