How would I convert swf to avi?

Do a google search for "swf to avi." There are a number of free converters.

You can try E.M. Magic Swf2Avi, maybe it will help you
http://www.effectmatrix.com/swf2avi/index.htm

Convert swf to avi needs powerful video converter, I personally think. After I try several video converters, I find Video Downloader Converter（http://www.downloadallvideo.com/video-download-suite） is a practical converting tool.

Here is a tutorial about how to convert SWF to AVI on Mac:
http://www.higosoft.com/convert-swf/swf-to-avi-mac.html

The tool mentioned in it also has a windows version. You can pick one according to your need.

hope it helps.