Jeroen showed me several ways of using codeception in your refactoring process, ways I had never thought of like testing an API and testing system settings. He also triggered the audience to participate in thinking of ways to apply it which even led to the interesting idea of testing API documentation.
As for points to improve on; the talk as presented was solid. The only thing I personally missed was that the "introduction to codeception" bit was smaller than I was hoping for. But the focus of the talk is on refactoring and that got the attention it deserved.
Clear presentation, engages the audience. makes sure the audience understands the applications can be very practical so that it is not just another academic presentation.