Glad we might actually see some justice here but of course it only happens when the officers are black. The video must be horrific judging by the reaction of everyone who has seen it (including the police chief). They are already begging people not to riot.
The only thing I can think about this is that the footage is so horrible that the pigs and the Memphis city government are literally, viscerally in fear for their lives and don't think a cover up would save them. I can't come up with any other explanation for their behavior than that they genuinely think they can't bring the boot down hard enough to save themselves.