Well, I don't know what everybody else thinks about it, but I think it's a crock. It was uploaded on the 15th. I believe that was just one day after the shootings, right? Still lots of confusion, and the media has no qualms about reporting on stuff before it's reliably confirmed as fact. NBC just got it wrong. Now there's a surprise, eh?
Also, clearly the weapon being retrieved from the trunk of the car was not an AR15. It was a shotgun. You can see a shell being ejected as the cop actuates the action on the side of the weapon. An AR15 is not racked from the side, it's racked from the rear, where the stock meets the upper assembly. You can also catch a glimpse of a thumb-hole stock at about 1:29. That was clearly not an AR15.
That conspiracy-theorist crap was uploaded before the bodies were even cold by someone who doesn't know the difference between an AR15 and a semi-auto shotgun like a Beneli or Beretta or Remington 1100. I just wasted 2 and 1/2 minutes that I'll never get back watching it, and it didn't take any longer than that to debunk it at the same time. It's total bunk.
BluesStringer, well said. I didn't even watch the video this time, but I watched it a few days ago and it's BS. I can't stand conspiracy theorist. They're as crazy as the gunman.