But the extension doesn't need to use that exact mechanism, and the person that linked it didn't mention specific mechanisms. The purpose of the extension is putting the real URLs back, and it can still do that.
And it can still prevent google from knowing which search results you click on, even though OP didn't mention that feature.
> But the extension doesn't need to use that exact mechanism
How do you figure? How else could it possibly work now?
You can read the extension source, and description. It is obvious that what it does is strip url parameters and decode well known google encodings.