I had the same confusion with his comment but I think what he meant was that when you highlight a result in a link, pressing enter causes you to follow that link (which is true). You are correct that ' focuses on only searching within links though.
Enter never goes to the next result though, so I am not sure if that is just something different between his setup and mine. I have to use F3 to go to the next result.
It's ' to trigger quick find in links only mode.