See the series of photos below for a demonstration of Grasp the Sparrow's Tail as a take down. Note that this series of photos were taken at speed to give a real sense of how this technique works. I am wearing blue in these photos, standing on the left side of the photos.
My duifang reaches to grab hold of me with his right hand & I respond with lu catching his center.
Having control of my duifang's arm, I turn my waist leftward & swing his arm to the side while I bring my right arm up between us.
I then turning my waist rightward to split my duifang by pushing his body downward with my right hand by applying pressure on the side of his neck while at the same time my left hand swings his arm in a different direction behind his back.
I continue this movement forcing my duifang lower while twisting his body out of alignment by forcing right arm back behind him.
I complete the throw by shifting my weight forward.