That tool was built many years ago by a researcher in Adobe's security organization. I do not believe that it's actively developed or maintained. It's built on Adobe AIR (which reached EOL a few years ago), and I think there's source code available if you wanted to try and build it against a newer version of the AIR SDK or something.
Personally, I've been using a tool called SWFWire Inspector for the past couple years. It's free. Also built on AIR, but worked fine last time I checked.
Thanks Jeromie_adobe . I give it a try .