the grip on the bow is actually incorrect throughout most of this scene (when playing the violin, the tip of your pinky should be on the top of the frog, not on the side with the other 3 fingers--there's a couple frames at around 0:05 where the grip is right) but the animation of the bow itself moving, the shift into higher positions & the animation of vibrato is excellent esp at the low angle at 0:20ish. love it when animators are able to do well acted string instrument scenes