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.

You can do the conversion with the helpf of this tool: http://www.kvisoft.com/swf-to-video-converter/
I used it for many times already.

You may need some third-party software tools for this conversion. For example, you could use Moyea SWF to Video Converter Pro to convert SWF files to some other popular video formats. You can check more in this post:
https://www.leawo.org/tutorial/how-to-download-swf-files-and-play-in-swf-player-1077.html?tw=#1389