For an attentive study of the work of others, an analysis of their design decisions, understanding one or another moment when Flash technology was chosen in their designs, it can be quite helpful to download what you find an interesting Flash clip in an editor and scrutinize it in frame by frame mode. I want to warn you from the get go that this does not decompile an SWF file in initial FLA format, but nevertheless it gives sufficient food for thought while studying great work.
Lower in the picture is shown the beginning of a protected SWF file the header in which is written its fundamental characteristics such as the following: the title of the format, Flash version, file volume and bytes, clip sizes by width and height, frame frequency, the color of background and presence of protection against importing to some Flash editor. Bytes responsible for the latter are highlighted with red ink in the picture. Removing Flash protection is a fairly easy process: simply delete these two bytes 00 06 in any editor which allows you to work with HEX codes, for example in UltraEdit. After their deletion, the file will become correspondent with two bytes and will be downloaded to a Flash editor without problems. For greater precision it is possible to decrease by two units the meaning of the address 04h, but for a Flash-editor this is not critical.

Of the information which is located in the header, attention is given to the following addresses:
00h-02h file format shown - SWF
03h version of Flash, in this case Flash 3
04h-06h - volume of file in bytes
11h-12h frequency of frames in Flash clip, here 12 frames/second (OC in a 16 tiered system)
17h-19h color of background clip, in this example white (FF FF FF - red, green, blue accordingly)
As already mentioned above, decompilation of an SWF clip in FLA format is basically impossible. So, other than studying such files, theres nothing to be done with them; in other words editing a file is out of the question.