I have a theory about how the shell casings ended up in the main bedroom, If Nevill was shot on the stairs. Whereby three casings bounce off the wall while a single spent case gets passed the wall and onto the landing.
Since I cannot attach video in the forum I have uploaded it here.
https://expirebox.com/download/810f54db1bd496d0a073494610263da0.html
I would like to put this theory to the test. But I cannot see that happening any time soon.
I haven't watched your video but I presume the theory is the same as we have discussed previously.
A few problems were identified.
1.
It's been stated that the cartridges travel about 4 feet when ejected, or could bounce on a hard floor another couple of feet, making 6 feet in total.
Your travel distances appear to be much greater, plus the floor was carpeted.
2.
You seem to have bullet casings becoming ethereal and magically passing through the door leaf to their final resting place.
3.
The distances that the shots were fired from, given by the pathologist, appears at odds with your theory.
Obviously you want your theory to fit your conclusion, I get that.
It seems more likely that the shooter was in the bedroom with Neville jumping out of bed, running past the shooter and downstairs, receiving shots just before or during his flight.
It seems more plausible than your convoluted 'Ricochet Theory'.