Eltima Software has posted a screencast on restoring an FLA or Flex project from SWF using Flash Decompiler Trillix. You can find it at http://mac.eltima.com/swftofla-converter.html; click the Play button on the left hand side of the page.
Flash Decompiler Trillix for Mac (formerly known as SWF to FLA Converter) converts Adobe Flash SWF files back into FLA format and SWF files created in Flex back to Flex sources, which can be edited in native Flash or Flex environment. Every group of objects such as morphs, shapes, texts, fonts, sounds, scripts, etc., are placed in separate FLA library groups with appropriate names to simplify using and working with the resulting FLA file.
Flash Decompiler can extract any object (images, sounds, videos, shapes, text, morphs, scripts, etc.) used in SWF files into various file formats just in several clicks. The latest version has a interface with tweaked navigation and preview options for SWF files and their elements.