Unlock SWF can open compressed SWF files and save a SWF version 6/7 file compressed or uncompressed.
While there are many SWF unlockers (Protection removers), Unlock SWF offers 'Debug Enabling' which is a feature that as of now no other utility offers. It's developped by Manitu Group (which has SWF programming experience since 1998) and it's free!