Yes, drop spin. I am a proponent of not overthinking the dropball.....to me the release action is just the same as a good I/R fastball....then get your body posture nice and upright/vertical and you have all the ingredients for a dropball. This little "crossfire" drill forces a natural I/R fastball/dropball release action.
First time viewing, it doesn't disappoint! DD will try the K style drill, it differs from hers. The posted K drill has less movement and appears more refined, thus more controllable and isolates the arm. We use the drill to loosen the arm and feel whip, so we can eliminate the footwork DD does.