Have you ever noticed this strange point in running where you just left the ground and suddenly your hind leg starts moving forward and your front leg starts moving backward? The faster you can make this switch the faster you can run. The impact on landing with this exercise closely resambles this specific moment in time. Therefore the landing should be hard, not soft.
The other part of this exercise is switching legs. With the additional weight pulling you down you have either to jump higher or switch faster. You have to prevent jumping and keep down as much as possible. You will find this easier as the weight increases.
Start of this exercise with just a stick or holding a heavy ball over your head.
Advanced athletes can go up to their body mass.
You can do this exercise both endurance, upto 6 series of 20 jumps as well as for power increase 3 series of 6 jumps. The exercises Mini Snatch and Tugo Walk are great supporting exercise to create the nessecary stability for this exercise.