I second this. Did this all the time as a kid. Not sure how well it taught but path but it taught me to unload and uncoil at just the right time, keeping my hands in front and letting the bat head develop momentum.
@volbeast33 how old of a kid we talking about? Swinging level isn’t such a bad thing to start out with if he’s like 7-9, you can teach launch angle and all that other stuff later when they have the strength to drive a ball in the gap.
This guy talks about proper posture driving the bat path. I too see kids stand up straight up rather than “butt out, chest forward” never thought about that creating the right path but he’s right. Really seems like if he’s got that posture and he learns to bend that back leg it will naturally take the bat along the right path.