In summary, the conversation discusses a model of a railway and canal, with the model being on a canal boat next to the railway. The conversation also mentions a bit of dirt on a computer screen, which initially appeared to be flotsam on the canal's surface. The conversation then briefly discusses a demonstration of water flow from an orifice at 08:58.
There is a bit of grease/dirt on my computer screen. At one point, it looked like it was some flotsam on the surface of the canal. As the camera panned across the scene, the flotsam drifted along the canal in a most realistic way.