Yeah, he’s kicking his legs out in front too much. I made the same mistake at first.
When you do the drill I’m describing (I might try to post a video of it if I get the time), begin with a simple bounce on the ball of the foot with the ankle cocked but allow the knee to bend slightly so that the foot comes up and not out. After a couple of steps like this begin to lift the foot a little higher and step over the support ankle.