I think that North did only have 4 diamonds.
Here is the full hand:
After taking the
♥A, West did return a
♠ taken by South. The South player is a 'beginner/interm' and did ruff a
♠, did get Easts trump and then played
♦'s.
I think that even intermediates should see that they always have one more trick to loose - have one fixed looser left - and that the only possibility is a squeeze. They should not even know how the squeeze will work, but they should see that there is no way to make an extra trick. So why not run the
♥'s? Maybe one of the defenders will error when discarding, ...or you never know: you make you first squeeze.

(I thought to post this squeeze hand in the beginner forum, but maybe Roland would ban me then

)
This was the last hand of the evening. Everybody scored 4
♥= ; if you make 4
♥+1 here then you get an absolute top. This is MP's: scoring that extra trick can be more important then bidding and making a slam.