swftools
are a unique set of tools but lack some user friendliness. They can't even iterate over provided objects:
Only one file allowed. You supplied at least two.
$ swfextract file.swf -i 1,2
warning! You should use the -P when extracting multiple objects
$ ls
file.swf output.swf
$ swfextract file.swf -i 1,2 -P
$ ls
file.swf output.swf