This BBC documentary (59 minutes) provides a concise analysis of the issues plaguing the European monetary union

This BBC documentary (59 minutes) provides a concise analysis of the issues plaguing the European monetary union. More specifically former British MP Michael Portillo visits debt-stricken Greece. He believes that the euro crisis must have shaken the Greeks’ faith in Europe’s single currency and wonders if there’ll be a desire to revert to the free-floating drachma. In Athens, he meets everyone from a destitute young family to the former finance minister and the outgoing Prime Minister, and is surprised by some of their answers. Meanwhile in Germany, Europe’s economic powerhouse, Michael encounters the taxpayers who are paying most towards Greece’s mammoth financial bailout while having to watch angry Athenians burning the German flag. 
In 200 words, please address the following question: ‘What is the key challenge facing the European monetary union?’