Do you remember what you & partner have agreed when opening the 4441 hands? You will see from the earier Lesson that the bidding on this hand will go:
* Fourth suit forcing, which South can simply raise with four card support so that partner has a clear picture of the shape of his hand.
If you are unsure, and this happened at one table, the bidding could go:
Now South has a dilemma
1. He can't PASS.
2. He shouldn't bid 2H or 2S - which is a REVERSE bid and would show at least 16 points and a distributional hand at least 5 - 4 in the bid suits preferably 6 in the first bid suit. This would be game forcing.
3. He shoudn't bid 2NT; 15-19 HCP.
South now realising the opening bid was wrong, bid 2NT. North was excited and drove on to 7NT, which as luck would have it, was allowed to make.
The moral of this story is to ensure that your 4441 bidding allows you to have a second bid that either keeps you at the one level e.g.
1C p 1d p
or as in this case your second bid will be of a suit suit of lower rank than your opening bid, at the two-level.