At this late stage, South was a bit depressed, since he felt that the previous seven boards in the set hadn't been swingy enough to pull back anything like enough points. Being charitable to him, this could explain his loss of concentration in play.
South won West's Queen of Clubs lead, being sure of 2 club tricks eventually. With those 2, there were also 3 tricks available in spades, 2 in hearts, 2 in diamonds, making 9 in all. However, there was some work to do to get 9 without losing 5 in the process.
Since length in Clubs was likely to be with West, South decided it was best to play on Spades to start with, since if he finessed the Diamonds first and it lost to the King, East would return a club and if they broke 5-2 with West having the Ace of Spades as an entry, then he was down. By playing on spades first, then even if West had the Ace, his entry would have been prematurely removed. Even if West followed up by playing a low club, then if they broke 5-2 , East would have none left when he won the King of diamond, and if they broke 4-3 then the loss was only 2 clubs, a diamond and a spade.
However, when East correctly held off winning the first two spades, West showed two cards by false-carding Hi-Lo. South was somewhat taken aback at the sudden prospect of losing 2 Spades and without thinking it through, changed tack and played a Diamond to the Jack. This was a complete disaster, since the finesse worked! Now he was short of entries to his own hand to knock out the Ace of spades and off he went.
What an idiot! Of course, if East had had 5 Spades to the Ace, he wouldn't be able to set up an extra spade without sacrificing the opportunity of setting up an extra club for West. So South should have carried on with a third spade.
At the other table, the International expert made the contract without any hassle when he (?misplayed?) the hand and finessed the diamond at trick two and could now play on spades at his leisure.
A pseudo expert is one who works out what the correct play is at the start of a hand and forgets at half time. A true expert is one who makes the best of the cards as they lie.
If your are interested in personalities, the idiot South was Ron McEwan, North was long suffering Andy Wells, West was Tim Hanlon, and East Hugh McGann. The true expert was Paul Hackett.
One thing Ron got right was that he and Andy hadn't done enough to avoid
defeat. Even if he had made 3NT, they would have lost by over 40 Imps.