It's an interesting explanation, but not a very good one, since he trying to pin it all - without saying so or maybe knowing so - on the Coanda effect. In fact the Magnus effect is an example of Kutta-Joukowski lift which is the mathematical formulation of Frederick Lanchester's circulation theory of lift, Basically if you superimpose a vortex on a uniform flow, there is a sideway force on the vortex. In an aerofoil the vortex arises because of the shape of the section; in a rotor it arises because the rotor drags air round with it.
The turbulent wake is a red herring too - he took that picture from wikipedia ...
