Introduction
The lesson video is the following
Main position
In this lesson we have seen how to invade in the following situation.
Invasion at A
The following sequence is usually played after the invasion at A.
Black mistake
The move at 8 is an overplay. Indeed, the sequence 9 to 13 capture the stone at 6.
White mistake 1
The move at 5 is a mistake from white.
If white does not push on the correct side then black can block at 8 and this time the tiger mouth prevent the cut.
White mistake 2
The push and connect at 7 seems very tempting, but is a terrible mistake from white.
After the normal jump at 11, black can cut with 12 and white dies due to a shortage of liberties.
Black blocks
Black can block at 4. In this case white must sacrifice his 3 stones.
After 15, white can be satisfied by the invasion as the corner is destroyed.
Invasion at B
The goal of the invasion at B is either to connect underneath or to live inside.
White connects
Following the sequence shown in the next diagram, white can easily connect.
White lives
The key moves after black block are the jump at 3 and the extension at 5.
The connection at 13 is sente as otherwise white would go out, so white can live with 15. After that white is alive even if black descent from 10.