The first time I seen the video I also thought the item in hand was an envelope. If an envelope, it may have contained drugs or more likely money. But I still think this will get tied back to SS and her brother, so that doesn't include drugs or drug money.
Given SS and MG were both shot behind the right ear, I wonder if there was another person in the car. Like someone said earlier if they were shot and placed in the car, why not put them both in the back seat? I think SS was shot while in the front seat of the car. MG was likely as well shot in the car in the back seat.
One person driving KIA, one person in the back shooting, one person driving the truck.
Car being parked must not be on camera or that would have maybe showed two getting out of the car and we would be hearing of three POI. So did back seat shooter person, if there was one, get out and get in truck before arriving at the apartment complex?
JMO