I too have flown a metro where the fuel would often flow from the low tank, apparently it had somthing to do with the flapper valves coupled with a bit of hockery pickery pressure imbalance between tanks.
I think on this night these lads just had too many things conspiring against them; the difference between the given result and one of "scratching it up too experiance" was probably about 1 second.
It certainly makes one reasses your own mortality