There are 3 main reasons why people jump forward on Snatch: (a) shifting onto toes right off the floor, (b) during transition passed the knees they shift their hips too far forward, or (c) they simply smack the bar out in front from the hips. I suggest coaches identify which one their athletes are doing then address it accordingly. To simply see an athlete jumping forward is one thing, but to identify why, or when it occurs, is most important. The line in this video is not to show bar path but rather to label the frontal plane, where the bar may not pass.