This muscle is notoriously tricky to isolate with a stretch, for a lot of people; and my 'Practitioner Hanging Fascial Pec Minor Stretch' partner stretch came about from my playing-exploring with ways to find a tangible and workable sensation of this region in my own body. I am really loving this stretch at the moment (and a couple of other hanging stretches); as it works great solo and *GREAT* as a practitioner (partner) exercise.
The second video is one starring Cherie Seeto (Sydney Stretch Therapy) has also come up with nice solo stretch (that gets pec minor and the clavicular fibres of pec major very nicely for me) - nick-named 'The Kebab'.(!)
This one works really well for me as a more active 'contract-move' eccentric style stretch, where the tissues are kept lightly contracted via a straight armed humeral flexion movement and slight elbow flexion; utilizing the breath to change the stretching vectors and release tension more specifically on the tissues attached to the ribcage (as opposed to a more standard contract-relax Stretch Therapy approach). Being a secondary breathing muscle, the use of various directed breathing techniques as enhancers to the stretch should come as no surprise.
Now, both of these stretches can be felt in many other locations - depending upon where you are have restrictions. Biceps and the fascia of the arms are very common. Both the Front Arm Line and Deep Front Arm Line myofascial meridians of the Anatomy Trains terminology are effected; and can be preferentially targetted if you know how.. different grip positions and strengths; different rotations of the humerus; different humerus to spine angles - and much more.
[ Check out the 'Arm Line' article here: http://www.anatomytrains.com/main/wp-content/uploads/2012/09/bodyreading1.pdf ]
Or just buy the new 3rd Edition of Tom Myers fantastic Anatomy Trains: Myofascial Meridians for Manual and Movement Therapists. The second edition is on my 'Recommended Reading' list for a reason.. I'm looking forwards to checking out the changes to the new edition myself!
Honing in on the pec minor for a moment (and related soft tissues of the Deep Front Line - esp clavipectoral fascia; subclavius), we can see via the anatomy of the area why this region is a potent site for the blood vessels and nerves of the arm to be compressed against the hard tissue of the ribs; and/or tethered and adhered within the soft tissues of the region (neuro-vascular entrapment).
Magnify the percentage chance of this happening in relation to the degree of Forward Head Posture and all its spine, rib and scapula correlates.
The chapter on the pectoralis minor in Travell & Simons' great work Myofascial Pain and Dysfunction: The Trigger Point Manual mentions a number of clinical manifestations of pain and dysfunction related to this area, including: golfer's and tennis elbow; carpal tunnel syndrome; various arm pain, weakness and loss of proprioception; and pain, swelling and altered sensations in the hands and fingers.
Taking a slightly wider, and more osteopathic/Daoist perspective (as I do); it makes sense to me that there could be(are) a wider range of inauspicious health, movement and sensory awareness impacts to having this area in a less than optimal state of soft-tissue texture and tone - even if these are 'sub-clinical' in that they have not manifested as pain or perceived dysfunction, yet.
Reading up about the meridian pathways of Chinese medicine can be very insightful when focusing on the sensations coming about in the whole body whilst stretching certain areas and maintaining sufficient body awareness and a clear enough mind. This complements the classical western anatomy and new fascial anatomy nicely (add in the Ayuvedic/Marma perspective for bonus points). The organ-meridian systems are also useful in watching various pulsations and other phenomena that appear post stretch..play with it.
Whether this is from a impingement upon blood-born nutrients or Oxygen (the primary nutrient) transportation; impediment of neural information; blocking of waste removal, or block of free flow of any other sort of information - the practical aspect of the effective re-patterning and softening the area is of primary importance in the Physical Alchemy method.
I have a fair number of variants and enhancements to the Practitioner Hanging Fascial Pec Minor/Arm Line stretch (needs shorter title..), that I will be recorded in the near future - stay tuned!