As with any tracked vehicle: Larger, flat surface area touching the ground results in better grip on soft ground and is less prone to sinking in. Small track-sections like here obviously aren't as good at that as full, tank-style treads, but easier to add to a wheeled vehicle and allow normal steering.
There's all kinds of companies making conversion kits to such (non-shape-shifting) small tracks for trucks and SUVs, not sure if there's a military example of that exact style.
The benefit of filming in the parking lot of the engineering building is that you don't have to drag your prototype and a film crew out to the nearest swamp.
