Grip issues. Epiphany!

that sort of swing will help with "impact". 

I think if you watch the videos you will find that many (maybe all) of the top players are constantly adjusting their grips depending upon the type of shot (serve, push, drive, sidespin, loop, etc.). The racket is held very loosely in their hands and they are constantly adjusting. 

Hi,

I will try to explain in words what most of the top players are doing, especially the Chinese since the Chinese I believe have a very different understanding of the game than you might find in other countries.

The top players are not choking up on the handle. they are resting their hands very comfortably on the handle. The V between the index finger and thumb are not choking up on the head of the racket. It is resting lower so that the head position can be easily rotated if necessary. Everything is relaxed. Not spaghetti relaxed however. As a shot is prepared, the racket is adjusted. You will often see this happening when  players switch from backhand to forehand but even forehand and backhand positioning changes depending upon the desired angle of contact, type of spin, height of ball, type of contact (brushing or direct), etc. If a player is choking up and holding the racket tight, these type of quick adjustments are very difficult if not impossible. You can observe Wang Liqin, Waldner, Samsonov, Ma Long, etc. during slow motion videos and you will get the idea.

Many players decide to choke up on the blade and hold it tighter because it gives them a more direct feeling of the ball when they hit it. However, learning you to hold the racket in a more relaxed manner and only pressing thumb and index finger on contact, allows greater fluiding, greater racket speed, ability to use the wrist, as  well as more options. 

This is not something that you can willfully learn. The only thing you can really think about is staying relaxed and over time building body memory and body intelligence. Then allow the natural body intelligence to choose the shot and position of the racket. It is like a basketball player who over time naturally learns how to shoot that ball into the basket. It is not something that is measured and calculated. The body develops an intelligence that does it automatically. But you will notice that all top players in all sports are usually very relaxed. 

Hope this helps.

Glad you enjoyed it. I keep reviewing the video to capture the image in my mind. He is very relaxed and uses his whole body in a very subtle way to coax the ball over.