First, West doubled the one no-trump opening, which by partnership agreement showed a long suit somewhere in the hand.
South played in three hearts after a one no-trump opening and another transfer response.
In the auction shown, the no-trump opening and the double were both slightly eccentric.
The two no-trump opening showed a minor two-suiter with 5-10 points.
Bidding in the face of a one no-trump opening presents problems.
That is because many hands with four diamonds qualify for a one no-trump opening.
In the other case it showed a minimum of 15 since a one no-trump opening would have been weak.
South has a standard two no-trump opening bid, and North naturally raises to game.
In the auction shown, North advertised 10 to 12 points with his one no-trump opening.
He used a weak no-trump opening, and his partner raised him to game.