Sometimes it is hard to debug SWF file, you need correct software to debug SWF file. You can simply debug the SWF file with SWF Decompiler. Like the name mentioned, the software is capable of decompiling, debugging, checking and viewing SWF & ActionScript structure.
SWF Decompiler allows catching and saving Flash animation for further editing by special functions. It recovers FLA from SWF or converts to FLEX source code so that you can extract all the elements (scripts, images, fonts, texts, audio and video) for modification. It even supports converting simple Flash to HTML5.
SWF to FLA/FLEX:
As you know, SWF file is not editable. However, SWF Decompiler can recover Flash document (.fla) from SWF and convert SWF made by Adobe Flex back to source code. You can also decompile the standard exe made by Adobe Flash to FLA, and extract SWF from Flash exe.
View SWF/ActionScript structure and extract element:
With the originated FLA or source code, you can check what does an awesome Flash made of and how does is code. Moreover, it is quite convenient to extract SWF element such as scripts, images, fonts, texts, audio and video. So this is a pretty cool feature for Flash design, teaching and learning.
Edit SWF elements:
SWF Decompiler supports edit shape by changing both figures and fill types or replace image, text and audio. Therefore, you can take best advantage of current SWF and make a brand new Flash work for your project.
Flash to HTML5 conversion:
It is capable of converting simple Flash animation to HTML5 format with great quality. So you can play Flash on HTML5 compatible browsers, which is pretty important on mobile platform.
Pros: functional interpretation on Flash decompiling, multiple support for Flash CS3 to CS6 and ActionScript 2 & 3, ideal tool for Flash design, teaching and learning.
Cons: cannot converting complicated Flash to HTML5, there are bugs in interpreting Flex file.