The governments of the old Member States realised that by the then existing rules, the mostly poor and underdeveloped regions of the new members would draw most of the structural funds, so they lobbied hard to (1) limit pay-outs to new members and (2) change rules so that they still get funds themselves. The governments of the new members were of course less than pleased, and lobbied hard in turn to get some last-minute concessions to show the voters. (I wonder how much of that came across for the makers and watchers of the video back then; but I suspect the "corrupt Eastern bandits wanted to steal our tax money and our bandit leaders gave it them" narrative was the easiest to apply.)

At that time, such haggling was better for everyone than either of (a) the status quo ante, (b) the prospect of trade wars, or (c) the prospect of actual wars. But when leaders (A) give strategic concessions while haggling for minute gains, without realising that those will be fatal, (B) lack the analytical clout, the boldness and the intergovernmental alliances to fight the problem when it hits (that is if they'd like to fight it at all), (C) or, being on the other side, don't see that extorting the others will ultimately hit back home big time; then all the petty-minded haggling with millions will contribute to one big train-wreck.

_{*Lunatic*, n.
One whose delusions are out of fashion.}