I don't understand German, but I assume the lady in the video is working on teaching her dog "away" and "come bye." I've worked on lunging the dogs in a large circle outdoors and on sending them around trees, but I think the visual perimeter that the small cones provide would be a great aide in introducing and/or reinforcing the concepts of "away" and "come bye."
Additionally, for general distance work they provide a clearly defined line that the dog is to stay beyond. You would begin with the cones forming a circle of perhaps ten feet in diameter and then expand it as your dog gets comfortable working at that distance. The only thing I would do differently is throw the treat or toy outside the circle the majority of the time to reinforce how much fun it can be to work away from the handler.