The new members ate up billions in what was essentially western charity, provided on the backs of western taxpayers, who were not thrilled. The new markets for western goods were essentially western capital temporarily sent east, to be spent back in the west again. As the east benefited, their own prosperity grew somewhat (the 30 to 70% mentioned in the video), but then comes the question if they can manage the rest in their own. Current indications are not hopeful. You dont wipe the slate clean of the effects of forty years of socialism with a wave of a magic wand, even if accompanied by a few hundred billion euros from the West. If all that creates is, e.g., a Hungary ruled by a neo-fascist like Orbán, then, then the westernization cannot be labeled a great successnot universally, anyway.
My wife got a good indication of that when a Polish caregiver for her mom arrived in January. She started feeding my wife with some right wing nonsense about how Germany was now the biggest taker state in the EU, largely supported by money inflow from Poland. Any look at an EU chart will instantly and definitively show that Germany is by far the biggest giver country and Poland is the biggest taker country. The propaganda war is already in full swing. Among the biggest exports westward, besides some cheap products, are poverty and organized crime. Some of this has come from beyond EU borders as well, of course. Gangs and clans plaguing Germany and the Benelux countries are not only from Romania and Bulgaria. They come as well from Albania, Lebanon, Morocco, Serbia, e.g. A few years ago, a gang of break-in artists from Serbia operating in Berlin used to kill anyone found unexpectedly in homes they broke into so as not to leave witnesses. They were only finally identified after they slipped up and left one victim alive, who later identified them. Incidents like this are not common, but they make for huge sensationalist headlines, which the population in the West remembers (note Serbia is not yet a member, whereas Croatia and Slovenia are).