I myself like a high elbow above the shoulder.I also like the throwing arm extended alittle back not the 90 degree to get momentum on the ball.Point ball to 3rd base.Land with the ball of the frt (lead)foot at 4o to 45 degree angle on a flexed frt knee(very important) then allow the heel to plant.Stride to step and think of the nose and chest over the lead toes.So I've been told and believe.Throwing is hitting and hitting is throwing.Your dd looks good.I also work on throwing with my DD every time we go out to pratice 3 or more days a week.