Hi Arjen,
That doesn't seem to have much to do with this Lesson, but there must be countless ways of doing what you want.
Here is a simple setup that Rotates Cubes on a Curve, depending on their Distance from the Camera, that is traveling along the Curve:
Just as an example of how you would be able to achieve something like what (I think) you want. (This is in 4.2 by the way, in earlier versions, you don't have Matrix Nodes, although you could still get the same result...)