I combined stroke mechanics and technique. If we distinguish them, then you are closer to the main point than I am.
And it is interesting. You guys are looking at technique and mechanics in terms of how energy/power is transferred into the ball. Which, of course, makes sense. And I am thinking of mechanics and technique from the standpoint of BIOMECHANICS, and how the body works, since, well, that is actually what I do.
This....the way joints work, our bodies....is also why everyone has a slightly different stoke. Everyone has a slightly different body. Longer arms, shorter, legs, torso, longer forearm shorter upper arm. One of the reasons, despite the steroids, that Lance Armstrong was so good at cycling had to do with the length of his lower leg in relation to his upper leg. Just take a few moments to think about that.
From the standpoint of joint mechanics, the simplest movement that will get the racket from the backswing to the followthrough while keeping the blade face in one plane, will be the basic mechanics you want to look at. And in that video of Sean O'neill, he is showing one of the biggest elements of that. Movement of the forearm at the elbow joint from the bicep. The whipping action that you need will come from if that movement is done in a relaxed enough manner with the right amount of acceleration. So, for a table tennis stroke, slow and relaxed is not going to work for spinning the ball. You need the relaxed part. But you also need as much acceleration as possible. That is part of the trick and the learning curve is to get that acceleration and whipping action that Brett is so good at showing how to develop in his tutorial videos. I mean, really, if you think about it, nobody else that I know of and have seen, has been able to figure out how to explain that how to cultivate that whipping action quite as effectively as Brett.....
So, the ability to transfer energy, and power into the ball, and the joint mechanics of the body, ARE NOT separate. Which is why that movement where the elbow goes up and causes the internal rotation of the shoulder, combined with shoulder flexion, and shoulder adduction, THAT IS BAD NEWS FOR YOUR SHOULDER. That is like trying to damage you rotator cuff muscles and manufacture an injury to the cartilage in your shoulder. In fact, that is almost the ideal movement for creating a forward dislocation of the shoulder joint. And these things I just said are exactly why combining those three movements of the shoulder joint--flexion, internal rotation, and adduction--WILL NOT CREATE AN EFFICIENT MOVEMENT OF YOUR RACKET. And will not allow you maximum racket speed or enable you to transfer energy/power into the ball efficiently, but WILL require more effort than is useful. And this will throw off balance, delay reset and cause a whole host of other mechanical issues.