I just watched the clip. The boy looks like he’s 12 years old. I’m not sure why some are darshening his words like a pasuk in Chumash. He easily could have confused Hitler with Goebbels or the quote of ‘kill the Jews like deer of the field’ with ‘until Jewry has been annihilated’.
As far as the boycott, I don’t think anyone doubts that it riled up the Germans. Of course the Nazis were a bunch of filthy murderers who hated the Jews from long before they came into power. But the boycott was a stick in their eye and gave them an impetus and a pathetic excuse to stir the pot against the German Jews now that they were in power and have the levers of government in their hands whereas they may not have been able to be so swift and brutal as they hoped without a pretext. It is never a good idea to poke your enemy in the eye. The boycott (which was publicly announced in front of 55,000 people in MSG and widely reported) and counter-boycott were much longer than a few days. And the German reaction to the boycott was the first overt official anti-semitic action passed in Germany.