This isn't exactly a "skull crusher" because you do it by lowering the dumbbells to each side of your skull. But basically you keep your elbows perpendicular to the floor while lying on a bench, palms facing each other, and perform extensions. Here are the advantages:

1. A neutral hand position helps keep your pecs out of the movement – something common with regular barbell skull crushers.
2. Unilateral stabilization forces more triceps engagement.
3. You can alter your form easily when you hit fatigue and extend the set, as you'll notice in the video.
4. They're superior to rope pushdowns because your elbows are away from your torso creating a better stretch.
5. There's also less torque on your wrists compared to pronated hand position variations.