This article's detailed analysis of the 180-degree shutter found on vintage film cameras shows why it's an effect that digital cameras are incapable of reproducing. The leading and trailing edges of the rotating mechanical shutter produce a smoothing effect that reduces the temporal aliasing inherent in sampling motion at low frame rates. Unfortunately, the electronic shutters used in digital video cameras work in a completely different manner that produces noticeable temporal aliasing along with rolling shutter effects. As a result, it's naive to apply the "180-degree rule" to digital cameras in the hope that it will duplicate the look of a motion picture film camera. In reality, there is no such rule that can be applied in a blanket manner to digital cameras - you have to evaluate the motion blur produced by the combination of frame rate and shutter speed on each camera to determine what looks best in your opinion in each case.