I've had that impression also (rc: that the shooter's path wasn't straight). The KRLD films seem to be consistent in showing that he came from between Sassa and Blackie, but the oddity is definitely there, as if he skips to the left before moving forward. And, as I've said, Blackie not noticing him hovering and shouldering between them seems impossible.
Davidson's film is even odder. It's hard to see but there is a flash and it looks like he's coming from the railing. Be aware that that's what several witnesses claimed too!