Dave Leys is performing a “crucifix”. Starting with two dumbbells locked out overhead, lower them until the arms are locked and horizontal. Though non-functional, this is a fun exercise. Mixed with handstand practice the crucifix is great training for an inverted cross on the rings. When you are able to lower dumbbells totaling your bodyweight to horizontal, hold for five seconds, and return to overhead you’ll be strong enough to hold, and pull-out of, the inverted cross.