He basically argued, that we mostly see the images and film reels of mass gatherings and Nazi parades in these documentaries without getting the context that these were all produced to create the image of "Ein Volk, ein Führer" - But it wasn't really that way in daily life.
I guess the answer to that would also touch the presentation of both World Wars in such documentaries.
Your question brings up several topics that have been central to some of my own research interests in the past.
First, starting with the visual history aspect in general: While such things as The History of Seeing have been published since the 70s, dealing with how photos are used as sources and in turn shape and influence how societies construct the past in their collective memories and narratives has gotten really big since the cultural turn of the 80s, i.e. using culture and its symbols as a way to approach past societies as well as how our own societies construct the past.
The problem your friend described is one that is very familiar with historians of Nazi Germany: That the wider social perception through documentaries and school books and other media relies heavily and often in a very uncritical manner on imagery produced by the Nazis themselves with a propaganda intent without at least attempting to deconstruct said imagery or put them in this context. The imagery of the jack-booted Nazis marching in rows while Hitler is whipping a crowd into a frenzy transport certain presumptions about the Nazi state prevalent in the narrative: The organization, Hitler as the lynch pin seducing the Germans, militarism, the uniforms etc. despite all this only depicting a small part of Nazi Germany's society and also being images that are manufactured with a certain intent. Filming a Hitler rally, it would have been unlikely to show people not being enthused but rather bored after the 4th hour of his speech. And even assuming that they were filmed, the imagery would not have made it in the final cut.
In his magnificent 1965 documentary movie Ordinary Fascism Soviet director and writer of the movie Michail Romm already commented on this fact. Romm made his documentary based on the film material the Soviet Union had captured from Germany (a considerable number of film meters), which he juxtaposed with his often quite funny commentary. At a key point in the movie, which deals with the subject of how fascism appealed to the German populace, he comments upon the fact that among the vast film material found by the Soviets in Germany, there is incredibly little portraying everyday life of the Germans during the reign of the Nazis outside of official party or propaganda functions.
In terms of visual sources, the glimpse into the ordinary life of Nazi Germany is hard to get. Even if it does exist, such as in an amazing project by the Hamburger Institute für Sozialforschung, which deals with the photos people made in Nazi Germany at these pass photo machines (the ones you often have at functions today, you know where people make a series of four photos making faces and fun poses), these often don't fit into the narrative that documentaries want to tell or have time to tell about the society of Nazi Germany.
Ultimately, this is also connected with the academic debates about Nazi Germany, since the very concept of Volksgemeinschaft has been subject to one of the most productive and interesting academic historic debates of recent years. Ian Kershaw, one of the most prominent historians of Nazi Germany, has given a run-down of this debate in his article „Volksgemeinschaft“ Potenzial und Grenzen eines neuen Forschungskonzepts published in the Vierteljahreshefte für Zeitgeschcihte in 2011.
In it Kershaw sketches out recent developments when it comes to a social history of the Third Reich and its most important milestones with the emphasize on the fact that from the development from the 70s forward has lead to historians recognizing more and more that anti-Semitism and the issue of race stand at the center of Nazi rule and ideology rather than being the ultimate culmination of it. As such, the Volksgemeinschaft has become regarded not as a failed propaganda concept concerning the Nazis' quest to solve class conflict but has become a lens and subject that can be grasped on three levels:
Volksgemeinschaft as a way to characterize the change of social and power relations
Volksgemeinschaft as a signifies for affective integration, meaning its use as a social utopian vision important in mobilizing and integrating social groups into the system of Nazi rule
and Volksgemeinschaft as a way to grasp the mechanisms and reality of social inclusion and exclusion in Nazi society.