This page doesn't explain what FFglitch does, or how it's different to ffmpeg. For instance, what's Glitch? I'm guessing it's an architecture, but the post doesn't explain what it is or contextualize the term "architecture."
The clearly labeled "What?" button at the top of the page explains everything.
From what i understand "glitch art" is using compression artifacts and encoding errors as art.
Presumably ffglitch is ffmpeg with code to fudge the file checksums so that encoding errors are allowed to accumulate instead of triggering an error.