1st Video: http://youtu.be/QKbAkFqRaBU : explains rounded/ protracted shoulder which is quite common posture in most of us (especially desk job) or an individual’s general tendency of adopting such posture after an injury (protected position). This posture over time decreases the subacromial space and thereby can contribute to impingement syndrome.
To prevent this; focus should be on :
a) appropriate stretching of pectorals ( Major & Minor) and their strengthening in full range of motion.
b) Rhomboids (retractor) strengthening.
c) Lower traps and Lattisimus Dorsi : These helps in downward rotating & retracting the scapula while bringing arm down from an elevated arm position.
d) Posterior Deltoid & Lateral rotators strengthening and stretching: these helps in clearing of the head of humerus while overhead activities.
2nd Video : http://youtu.be/3zPg8MnbYys ; Is very appropriate, as it explains most of the reasons that can lead to shoulder impingement and related issues.
3rd Video: http://youtu.be/WfyN1F0HCBk : Is self mobilzation of scapula ; which may not be appropriate for people with subacute to chronic impingement syndrome as the impingement range falls between 60 to 120 degrees. So, in these cases patient may have pain while achieving and then moving from that position. However, it may be appropriate for those who can achieve this position without pain.
We can use certain modified positions like modified plank , table top positions etc to mobilize scapula.
4th Video: http://youtu.be/lebhdCzf2XI ; Is general strengthening of internal & external rotators, but he should have used a pillow or towel in between the trunk and arm for additional stability and isolations of these muscles. Otherwise, many people may end up compensating these movements with abduction/ adduction of the arm which may lead to compensatory postures.
5th Video: http://youtu.be/TE3AF_NOw4s : Again, patient in pain wont be able to perform these motions appropriately. He didn’t use appropriate posture & there is lot of compensation ( e.g: lateral trunk bending while moving his affected shoulder , it will further lead to inappropriate posture and more compensation).
Also, In lot of individuals with shoulder issues, due to self imposed restrictions or pain capsule gradually becomes tight so its appropriate stretching very important, which can be achieved by by gravity assisted positions like prone on elbows ( posterior capsule stretching), supine on elblows ( anterior capsule stretching), and self self inferior glide can be achieved by holding a weight or a table and leaning on the other side.
There are lot of individual variations in postures that depends on several factors , however appropriate exercises can bring optimal results in most cases.