I was lucky enough to play a Japanese pro at a simul a few months ago, and we reviewed the game afterward. Whenever he was playing out a sequence, he could pick up several black and white stones mixed together and then quickly place them in alternating colors around the board with one hand, much faster than one would be able to place them by grabbing each stone from the bowl each time. (Maybe my description is boring – it was certainly very impressive in person.) Are there any other stone-handling tricks like this that you guys know of, especially ones that I might be able to learn?
I heard one, to hide skillfully 1 stone under the board. Very useful in close games.
More seriously there are some nice agility when counting the board for scoring. There is this trick to put chinese half convex stones at reverse when analysing positions.
There was a video linked here
Where a pro captures 4 or 5 stones and picks them up in one go but the link to the actual vid seems to have been removed