He's not saying black on black crime is to do with BLM, though - he's saying that if BLM actually cared about black lives (rather than the money, power and fame) they'd knuckle down and get to the root cause of why there's so much black on black crime (and deaths) and come up with tangible and practical solutions to help their fellow blacks out.
What they do does not help their black race.
What they (BLM) do doesn't do nothing, lots is happening due to them but it can argued most of it is either tokenism or flat out counter-productive.