A couple things: The Pt is holding the arm in a position of comfort so if possible you should immobilize it in that position assuming it isn't affecting CMS. Also, the side of your sling that goes under the arm goes to the opposite (uninjured) side.
Why did you publish this video, when the placement of the sling was wrong? The two ends (to be tied in back) are switched. He should've taken the INSIDE corner and gone to Pt's LEFT side, not the right - and alternately should've taken the sling he put on the Left onto the pt's RIGHT arm... and yes, it DOES make a difference, which is why there was such a HUGE gap between the sling and the base of the arm. This should be taken off until the CORRECT application is made.
Hi there. Sounds like a program specific rule to me. In a real-life scenario this would be a concern if there was torso trauma, trauma that wrapped the rib cage or the spine. In that situation those more severe injuries would take preference first and we would modify our approach to splitting the arm. I've had hundreds closer to over 2,000) test) using this approach with no problems. My recommendation is to continue performing as taught as they may test a little different. Take care and best of luck! RallypointEMS\Jeremiah