SWF Extractor does not have a setup application, just unzip the contents to a folder using any unzip utility like WinZip. SWF Extractor does not do anything the registry and also it does not create any unwanted files. SWF extractor works only with uncompressed files (version 5 or older).
After running swfextractor.exe, you can open a SWF by using the "Open and Extract all" button. The files would be immediately extracted to the same folder as the swf file itself. A grid below the button can be used to view the images and mp3 files extracted. Program will launch your default audio player to play mp3 files.
If you are willing to spend $4, you can buy SWF Decompiler,
which can extract images and mp3 from even compressed SWF files. If you want a Batch SWF Decompiler to decompile multiple SWF files at the same time, have a look at Batch SWF Decompiler
To download SWF files from your website if you have lost your FTP access too, you can use SWF Downloader.