Freeze the video during the slow motion as he is about to start his forward swing. At this point, his forearm and wrist are straight, so it seems as if he's not using wrist. But use the Youtube feature of hitting a period so you can move forward one frame at a time. (Use a comma to go back one frame at a time.) As his arm moves forward, shortly before contact, his wrist falls back, and then snaps through the ball along with the forearm. 

-Larry Hodges

Freeze the video during the slow motion as he is about to start his forward swing. At this point, his forearm and wrist are straight, so it seems as if he's not using wrist. But use the Youtube feature of hitting a period so you can move forward one frame at a time. (Use a comma to go back one frame at a time.) As his arm moves forward, shortly before contact, his wrist falls back, and then snaps through the ball along with the forearm. 

-Larry Hodges

Are you sure? It looks like it might be so but really hard to tell from this video and angle. There's not enough fps. Anybody have another clip because it doesn't seem to be any obvious follow through of wrist. Noticed Samsonov another tall guy does the same with wrist not moving or no follow through with flick of wrist.

https://m.youtube.com/watch?v=NhGTa-vNAqc" rel="nofollow - https://m.youtube.com/watch?v=NhGTa-vNAqc

1:05 go to playback settings slow mo it and see samsomov not use wrist.

Are you sure? It looks like it might be so but really hard to tell from this video and angle. There's not enough fps. Anybody have another clip because it doesn't seem to be any obvious follow through of wrist. Noticed Samsonov another tall guy does the same with wrist not moving or no follow through with flick of wrist.

https://m.youtube.com/watch?v=NhGTa-vNAqc" rel="nofollow - https://m.youtube.com/watch?v=NhGTa-vNAqc

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It's tricky to see because the racket accelerates so much as it approaches the ball, and the video speed isn't nearly fast enough to make the wrist motion clear. But see the four consecutive frames below (taken about 18 seconds in). Open all four up on a computer screen, if you can, and page through the first three quickly and compare. In the first one, wrist is straight. In the second one, you can just see that the wrist is falling very slightly behind, but it's subtle at this point. In the third one, see how the forearm is now a blur as it accelerates into the ball, while the racket and wrist are starting to lag behind, and so aren't as blurred. In this one you can see the wrist falling behind the forearm. (Key thing is he doesn't bring the wrist back so much as forearm accelerates while wrist lags behind.) In the fourth one, it's all a blur as the racket is now moving too fast for the video - and this is where the forearm and wrist are accelerating into the ball extremely fast, and where you could see the most wrist motion, if the video were faster and sharper. 

http://www.larrytt.com/images/wang-wrist1.jpg

http://www.larrytt.com/images/wang-wrist2.jpg

http://www.larrytt.com/images/wang-wrist3.jpg

http://www.larrytt.com/images/wang-wrist4.jpg

The angle and low frame speed (relative to his explosive acceleration before contact) make it hard to pick up the wrist motion on this or other Youtube videos - it's all too fast and last-second, and the wrist movement is only a few inches at the last second, compared to the longer (in time and distance) movement of the forearm. 

Here's one where you can see the wrist motion slightly better:

https://www.youtube.com/watch?v=zIImvHq-nz0&t=179s&ab_channel=AzlanOthman

Here are two frames take at 1:40:

http://www.larrytt.com/images/wang2-wrist1.jpg

http://www.larrytt.com/images/wang2-wrist2.jpg

In the second one, you can see how much more the racket has moved than the forearm, since it is the wrist flicking into the ball at the last second. 

Coaching the subtle wrist motion in looping and serving are two things that are very difficult to see on video, and are much easier to demonstrate in person. In general, top players use more wrist against a slower incoming ball, less against a fast incoming ball. (Samsonov notoriously uses less wrist than others as he is more control, less power.)

-Larry Hodges

Still tricky to see, other than the length of the blur of the racket. Also, there's going to be more wrist when he's looping hard than when looping steady. In the original video on this thread, he's not really ripping the ball, so less wrist. If he rips it, there's going to be a lot more - but that would just be a blur on video. In person it's much easier to show this type of thing. 

-Larry Hodges

Unless one literally locks their wrist (leading to a rather stiff and unnatural swing), it's natural to have at least some wrist on all loops. The forearm (probably the most important part) naturally throws the wrist into the shot. The only question is when to go for more wrist, and how (up/down, forward/back). Usually top players use more wrist against slower incoming balls, when they are going for rips or super-spinny loops. Against a faster incoming ball, such as counterlooping, they'll use less wrist in most cases. 

-Larry Hodges

It can be up-down movement, forward-back movement, pronation and supination or mix, without any of them it seems unnatural.

Speed gives forward

Spin gives up ))))

Power gives pronation

In my experience the wrist is not very powerful, I don't use a lot of ulnar/radial deviation or even flexion/extension, just a tiny bit. The major power source is the pronation/supination which I've learnt to use heavily, and I've also noticed the modern CNT relying heavily on it. 

See this. In fact if you have this mechanism, just turn it over and you'll already have good FH and BH arm strokes lol, and then you just need to add in the weight transfer and hip rotation.