“Aye, vot ey vot ey party! Let's save ze Vorld!” Müller exclaims in the video as he walks onto the stage to loud applause. “Two handret… two handrrret zeventy tousand people here. Velcome all of you!”
Speaking for a little over a minute, the Christian Social Union (CSU) politician merrily bumbles his way through his notes, sometimes speaking in quite fluent English, albeit with a rather strong accent, at other times getting his grammar in a total muddle.
“I lave you. I'll be lav here to be viz you,” he shouts at one point. “Ve all in ze vorld, ve have von common vishen. To be vizout hanga.”
As one final flourish he ends with the pronouncement that “Germany is viz you… let's vatch a message of ze German Chancellor Angela Merkel!”
The video is fast becoming a YouTube sensation, having already racked up almost 100,000 hits as of Monday. One person has even sampled the speech to make a Denglisch techno remix.
The younger generation of bilingual Germans take a special glee in watching their parents' generation struggle with even basic English grammar and pronunciation.
Southerners in particular are ridiculed over their strong accents. Müller, like all his CSU colleagues, hails from Bavaria – a state with a reputation for being insular and parochial.
In 2010, Günter Oettinger, ex-minister-president of Baden-Württemberg and then vice-president of the European Commission, became a laughing stock for a speech he made at Columbia University, in which he tried to talk about technology in almost unintelligible English.
On the Müller video, one YouTube commenter expressed his amazement at Müller's poor English, pointing out that he is Minister for Development and Cooperation.
"He must come into regular contact with foreigners for his work and converse in English," the commenter mused.
Others, though, have defended the minister, with one person saying that his enthusiasm counted for more than his linguistic ability, pointing out that "no one [in the USA] expects foreign politicians to be able to speak accentless English."
The decision to express himself at the event, which was live-streamed to an audience of 2 million, in a language with which he wasn't comfortable is without doubt a brave one, and something to be commended.
German politicians are not always so willing to give it a go. Former Foreign Minister Guido Westerwelle once refused to answer a BBC journalist in English despite being perfectly capable of doing so.
British and American politicians are never under the same level of pressure to express themselves in a foreign language, so can show off when they feel confident enough to do so competently.
Matty Edwards contributed reporting.