Introduction
The lesson video is the following
Main position
White wants to reduce the potential of black on the top and approach the corner at 1. Black wants to profit and building a big potential on the top. So black pincers with 2.
What is the best way for white to manage this pincer?
Usual joseki are wrong
If white tries to go to san-san, he will fall into black trap. Indeed the following joseki would follow.
After this joseki, white is in trouble! Black has made two massive walls and it will be hard to reduce.
It is even worse if white tries to jump out. The following joseki would follow.
After this, white has nowhere to go and is a floating group. This joseki is only good if we want to get influence in the center.
Finally, the double approach lead to better results but is not optimal. Indeed after the following sequence:
The normal joseki would be to play A, B, C but in this case it is better to follow with the next sequence:
With the sequence 1 to 3, white reduce black influence. This is a better result than the previous joseki, but there is a better solution.
Attachement first
White can start with the attachment at 1. Black must protect at 4 and after white extend at 5, black has a weakness at A.
Black ignore the weakness
If black ignore to protect at A in the previous diagram, then white will cut and the following sequence should be played:
The moves up to 16 are joseki and white finishes with sente. He can tenuki and do something else. Although white group on the top is not 100% alive, black ends up very over-concentrated. This is therefore good for white.
Black connects
So black should connect at 6 and the joseki shown in the next figure is played.
Black marked wall feels over concentrated so white can feel happy about the result. This is the best result for both.
White sacrifice
If black tries to block the other way with 12 then white must make a useful sacrifice with the following sequence.
With the move up to 25, white sacrifices the 1,3,5 stones and use them to built a huge territory on the left side. The left side is too big and this is definitely good for white.