There are four problems and the solutions are given in his J-Group video. The idea is to try to solve them before looking at the solutions…
The key points that solve this problem are needed for the following three problems.
White played F2 and Black made the tiger mouth. This is wrong: prove it (White to play).
White played F2 and Black descended, what is the best outcome? (White to play).
White to play and improve on F2
David Mitchell provides the solutions and discusses life and death generally in this video on our YouTube channel: