I think the yelling stim at this point is Abbies way of getting attention. Yes,she may find it a comfort for whatever is going on at that moment,but,at the same time,since she was younger,they have let her basically do it without any sort of intervention. There is an earlier video of Abbie( she’s approx 5 yrs old,) where she is running non stop around the living room, bouncing from sofa to chair,yelling continuously,all while Asa films her. The video is approx 2 minutes long,and that whole time,he never once puts the camera down,tries to calm her,distract her. You see a shot of what I think is the kitchen where a gate is up,and PityCilla is sitting with Isiah at a table. (Maybe eating dinner). She doesn’t move either. If the vid is 2 minutes,wonder how long she was actually going about that behavior in real time? At one point,it appears Abbie realizes the camera is going,comes right up into the lens,smirks somewhat,then turns around and proceeds to continue the behavior all over again.
Had that been being addressed all this time,it may not be as (still might happen) ongoing/bad as it is today.
As to the staring,we all do it! Even myself,the Gramma to an autistic child,will still look if I see a child(even and adult) who is in distress,showing loud behaviors,etc. Doesn’t matter if they have challenges or not.