hello matthiasi suggested you a very small & simple change which can be usefull in swfextract.c
line 9 in function handlejpeg replace filename ="output.jpg" ; by filename =name ;
like that each jpeg file will be named differently picXX.jpg
same in line 85 in function handlelossless ( for png files ) replace filename="output.swf" by filename = name ; each png file will be named by picXX.png XX is the number shown in the no option swfextract command