Using fdb to debug.

how_to_use_fdb.txt

1) Execute 'fdb'
2) Initialize a session typing 'run'
3) When you open the SWF file fdb will output this:

Player connected; session starting.
Set breakpoints and then type 'continue' to resume the session.
[SWF] path:file.swf - N bytes after decompression
(fdb)

4) Then you set your breakpoints. E.g: To set a breakpoint in the line 100 of your Main.as class, you will use:

b Main.as#100