Thinking about this a little more Roy I am not certain that what the guy is advocating is correct. The standard rubber bushes are loaded when they are installed correctly, they are not designed to move freely. If I remember correctly when you install new bushes you are not supposed to tighten the bolts up until the arms are in the horizontal position. That Loading of the bushes forms part of the calculations when calculating the spring rates for the car. It seems to me that the poly bushes imitate that loading characteristic to some extent, whether increasing the loading, stiffer suspension or standard. The point is that the designers did not intent for the arms to swing freely as in the case of the super pro bushes. I'm not sure if freeing the movement is as desirable as the video suggests.
Mike