The point is repeatedly made that the part score area is a “battlefield” where most of the match points are won. Going one down against a making contract will get you a good score but he urges caution when the vulnerability is unfavourable (you are vulnerable and they are not).
The Presenter spends a little time on The Law of Total Tricks as a guide on when to overcall, especially when the opponents have found an eight card fit. He defines a sacrifice (“I know we are going down but expect to get a better score”) and how to chose between No Trumps and a Major suit game.
The main point is to bid high and fast in support of partner, a message we can all learn from!