The best open source alternative to StepShot is Dokit, which is both free and Open Source. If that doesn't work for you, our users have ranked nine alternatives to StepShot, but unfortunately only two of them is open source.
Dokit makes your documentation accessible in just a few clicks on all media (PC, mobile, machines) and integrates with your existing systems (CMMS, PLM, LMS). Easily adapt the platform design to your graphics. Enable single sign-on to make it easier for your users to log in.
xsr - X Steps Recorder This program is a clone of PSR for Windows, a program that allows users to make a recording of all of the steps they took. (It's like a screen recorder except it doesn't record a video.