“The Twitter video made by some girls in a house across the street from the door clearly showed the shooter simply opened the door and walked in. Either the door was propped open or it was unlocked.”
Can you share a link to this video showing a door being opened? The only video I’ve seen is from the side, and the entry is obscured. The door is recessed several feet into the building.
https://www.youtube.com/watch?v=BO-AJiydlLM
You can’t see the door but the shooter walked in easily. As to the two guys at the 11 and 12 second mark I took a screenshot and enhanced it with editing software (Gimp). The object between the two people certainly looks like a rifle with a magazine. When enhanced a sling becomes visible.
If it were something else what could it be?