With 8 points, and 4-4 in Hearts and clubs, the best bid by West is a Take out double. North puts pressure on the opposition with a simple raise to 3D. East west bid game. South must avoid the temptation to lead the Ace of diamonds, which may give the contract. The best lead is the King of clubs. North realises that South must have the Queen of clubs as well, so overtakes with the Ace, and returns a diamond. South makes 2 diamond tricks, and awaits a spade trick.

Gambling 3NT! South will pass it, since there is no guarantee that the opposition will find a spade, lead, and even if they do, the spades may be 4-3, or 4-4. On a club lead 12 tricks will be made for a top! 

Alternative, if you play 5 card Stayman, you bid 3NT over 3C . The important thing here is the timing of the play, to make the most tricks. You should aim to make 12 tricks wherever possible. Let’s say North leads a neutral club. What you don’t do, is to play off 5 club tricks immediately ! You are now limited to a maximum of 11 tricks (possibly only 10). You win the 10 of clubs at trick 1. You finesse the Jack of hearts at trick 2. It wins ! You finesse the Queen of diamonds at trick 3, it also wins. You play the 10 of hearts, covered by the King, and won by the Ace. You return to dummy with the King of clubs, and finesse the Jack of diamonds. You now give up the Queen of spades to the Ace. Claim the rest. You have 3 in each red suit, a spade, and 5 clubs = 12 tricks.

The redouble by East shows at least 10 points, and does not hold at least 4 hearts (else jumps in hearts, or bids 2NT).

You will all question the 3♠  bid. North heart holding is good - the King is worth a trick; South may have a void or singleton, and East – West are obviously not super strong (Probably 10, opposite 10); N-S are Non-Vul. So South will be able to ruff a couple of hearts, as a Reverse dummy.

The Winning lead!

Why does North not bid Stayman? Because the hand is a flat 4-3-3-3, with no ruffing values. What should West lead?  A diamond is not good, nor is a club from J9 to 4 safe. A major lead is preferred on the bidding, where neither hand has shown interest in a major. Make a lead in the longer suit, and lead second highest from a bad suit, i.e. the 7. Declarer will possibly try the 10 (the lead could be 4th. highest, after all), and now, East can win 2 heart tricks, and West the Ace of diamonds, to keep the contract to 10 tricks. Any other lead, Declarer has 11 tricks.