This looks so easy, but it is not. Controlling the weight over your head while moving is an excellent exercise for your core. This exercise focuses on the coorodination between the back, the abs and the hips in one go. Alternatively you can use a plate, a waterbag or two dumbbells. However I think the barbell is the best; a plate is maller and less of a challenge; the waterbag is too wobbly to keep posture and the dumbbells let you take control with your arms instead of your core. Nevertheless some athletes find it difficult to get enough weight overhead to make it a good exercise, in that case I move to the waterbag.
The cones are there on purpuse, to prevent shuffeling