One player committed fully to the leap. The other committed fully to the ground. The timing made the whole thing look choreographed.
Australian rules football moves fast and contact arrives from everywhere, which produces collisions that look chaotic frozen and perfectly normal at game speed. One athlete is airborne and determined, the other is sliding through on pure commitment, and the camera caught the half second where both plans peaked at exactly the same time.
Australian rules has no offside, so players attack the ball from every direction at once, which is how one athlete ends up airborne over another mid-contest. The leap was legal and fully committed. The timing made it look rehearsed.