Great talk about hexagonal architecture.
The talk starts out by motivating the need for a consistent and maintainable architecture.
The next part is quite technical and introduces the concepts of hexagonal architecture. Since this part is technical and somewhat abstract it's a bit harder to follow.
The part about layers came somewhat out of the blue and might benefit from showing an additional example of layers that are often used (i.e. after the slide "Mmm... layers" you could add a zoomed out version of the slide showing the Infrastructure, Application and Domain layers).
Since all participants were speaking Dutch the talk was presented in Dutch. This made the talk somewhat less formal, which is nice for a meetup.
It had the "disadvantage" that some of the technical terms on the slides had to be translated to Dutch, though I don't think this had much negative effect.
Overall the talk was very interesting and motivating to do delve deeper into architecture design.