First, download standalone Adobe Flash Player
https://www.adobe.com/support/flashplayer/debug_downloads.html

Then click "File, open location (Ctrl Shift O on windows, Cmd Shift O on mac), then paste the URL where the URL goes.
https://battlefordreamisland.com/5b/c.swf?path=5b.swf

Click "OK" and there you have it! 5b is playable in 2021.

coppersalts.github.io/HTML5b

Note that we are not running speedrun.com leaderboards for the HTML ports yet.