It's just to build the muscle memory. If you've practiced a finish 100's of times then when you are under pressure your technique can just take overTo be honest the shooting practice in the video released looks very very simple to me. I don't know if its to give them confidence or whatever but to me it seems almost pointless. I've done shooting practice with kids more challenging than this.
Having said that I'm good friends with a striker who used to play for Denmark and him and a teammate spend a summer doing simple shooting practice like this and he scored a bunch of goals the following season..