In my first response to this thread i was being somewhat facetious. Hopefully there is really no hit the fleeing felon simulation training in S. Carolina (or anywhere else for that matter).
In all fairness (I try to be) and if I may, however, play the devil's advocate (no pun intended); the nature of the job is perhaps something to be also taken into account regarding this incident. I'm not saying it was right, not saying it wasn't racially motivated, certainly, at least, an excessive use of force...but possibly also a result of the environment in which they work.
Admittedly, I have friends and even relatives who a members of some police force, someplace. I've heard personal accounts of incidents (by black cops, dealing with black perps). Let's just say, the things they may find amusing (or may even brag about) are not within the range of what the average joe would find "appropriate". This is so of doctors and nurses too.
I've seen guys who were basically good and kind-hearted people develop a hardened and even callous attitude about the kind of people they deal with on a daily basis, (no not kind meaning race - but kind meaning people out there who are usually up to "no good") and do so in continuously adversarial and sometimes life threatening situations.
Many cops go overboard. In the heat of the chase they cross the line between "protect-and-serve" and "excessive force". Throw in the animosity, the frustrations of the job, the general enmity (or indifference) of John Q Public... then toss in racism (in those cases where it exists on a personal and institutional level) and you probably have small wonder that more such incidences don't occur.
Well, guess what...they do. You just don't hear of them.