Without being there in person to poke and prod at you, there is not a lot more I can do from here. If making the various adjustments in the videos and working on the stretch that Horn goes over in his video doesn't help, then maybe you need to squat high bar. You can live a full and complete life training the high bar squat, but you will not get the secret decoder ring that low bar squatters earn after they master the technique. The other thing you can do is see a coach and perhaps they can help you. There are some people's shoulders that just do not agree with the low bar position. Cannot say if that is you from here, but maybe it is. Then again, maybe not. Why is a mouse when it spins?