Ahh youth soccer at first i thought it was just kids falling down and the camera pants out to the side a bit. but it looks like the kid who initially has the ball sees the other player approaching and leaves to the ball to hip into him and prevent him from getting it. So I would call that a foul.
Youth game kid in possession doesn't play the ball and recklessly fouls the opponent. Call the foul and talk with kid to let him know that he can not do that in soccer. Teaching lesson for a youth game