Introduction
The lesson video is the following
Main position
During this lesson I learned a trick move within a classic joseki.
This kick is super well-known and give a good result for all. As all trick move, the end result for black is not as good as this result, but it is not terrible neither. This makes this trick move playable.
The trick
Instead of jumping at A like in the normal joseki, black con pincer with 4!
The correct variation is as follows. If white plays like this, the result is slightly comfortable for white. The key move is 9. Indeed, black cannot play the cut by playing 10 at 11.
Black Overplay 1
If black tries to cut, white can counter-cut and black is heading to a disaster.
After 21, black has totally collapsed! That is why black cannot fight with the cut at 10.
Black Overplay 2
If black tries to generate some cut with 1 in the next diagram. White must defend the marked stones as this is the weakest group.
So white must defend by extending at 2 in the next diagram. The forced sequence follows and it is a conforable fight for white.
White falls in the trick 1
Very often (and this is confirmed by my own games!) kyu and low dan player will falls into black trap and play the move at 9!
Although it is a sente exchange, this is very bad for white. Now white cannot hane at 12 and must extend, letting black going out while having a corner 100% safe.
White falls in the trick 2
I used this trick move in some of my game, and this sequence happened.
White tried to respond by going to the san-san. The right way to handle it is as shown in the next diagram.
After this, white becomes a floating group that needs to run out while black makes territory. White has definitely fallen into black trap.