Sometimes it can be hard watching the parody videos because, while I don’t speak it fluently by any means, I know a good bit of German and it is distracting to read subtitles for language that very obviously means something else. I have to make a concerted and constant effort to tune out my mind translating.
I have the same problem. To me, the Hitler rant videos that work best, and that allow me to disregard most easily the actual meaning of the German dialogue, are the ones in which the writers of the fake subtitles pay close attention to Bruno Ganz’s performance of each line (his tone of voice, his gestures, his emphasis of particular words, his motivation) and come up with clever subtitles which genuinely give the impression that this is what he’s actually saying and which form a coherent, plausible narrative. Ganz goes through quite a range of emotions in that clip, and a good parody dialogue will likewise shift in tone as the clip progresses to reflect this accurately. I think the “Hitler rants about the new Axis and Allies game” video is particularly good in this regard, with my favourite part probably being the line about the errata page.