This tutorial teaches you how to control the whole movement from the start till the end. I'd say that every one rep of these step ups is worth ten rushed step ups. Step ups, when performed well, load the glutes, hip flexors, quads and hamstrings.
Learning to step up and down well, also challenges your ability to stay upright and maintain the load through the lower limb, without tipping forward or deviating to the side and losing balance.
It can easily be done at home and is a great addition to a squat, and might even carry over to greater symmetry of loading into the squat pattern as well.