One of the keys to directional movement success if having a clear word that tells the dog to Move Laterally. In the videos the Instructor is using "Over". Pick any term for yourself that is clear to the dog and not readily confused for another command (e.g. "No" and "Go"). While not demonstrated, one might also consider having separate terms for moving Right or Left as this may be useful for both Balls In Order and Urban Herding.
The videos shared show a sequential steps for first introducing one's dog to the concept & command to leave one object/ball and shift laterally in the direction indicated to another object/ball.
We thank Monica Pielage for the first video featuring Joan and Tucker on how to introduce the dog to moving laterally.
The second video demonstrates the next step of slowly adding distance and using mats behind each ball to reinforce the correct position for the dog. Thank you to Monica Pielage for this video featuring Fabie and Storm.
In the third video Monica Pielage demonstrates WAIT & OVER working at greater distances and without the mat behind each ball. At this stage one could add more balls.