Hi, what is this line between Guintoli and Lorenzo? It always moves from the top to the bottom and after watching MotoGP for forever I still don't know what it means.

https://i.redd.it/m34ik5qz6yj31.jpghttps://i.redd.it/m34ik5qz6yj31.jpg https://i.redd.it/m34ik5qz6yj31.jpg