Posting this here in case it's helpful to anyone. Now that Flash can no longer be used in web browsers, it's difficult to play back archived PhotoShow files. You can still, however, use the stand-alone Flash Player Projector to play Photoshow *.SWF Files.
As of the writing of this post, you can still download one of these projectors here: https://www.adobe.com/support/flashplayer/debug_downloads.html
If that page is no longer working by the time you read this, search the web for a safe location to download flashplayer_32_sa_debug.exe.