Thanks for fleshing this out, Nick. Also unrelated to your OP, other German movies, fictional but topical:

Persian Lessons (2020) A concentration camp inmate survives so long as he is teaching the Kommandant Farsi, which he does not know.

The Lives of Others (2006) A post WW2 Stasi (East German security) officer gets caught up in observing artists that he knows socially.

Again, getting back to the film clip that has so captured our imaginations, I saw this so many years ago that I knew it was authentic, but not sure authentic 'what'. These days it could totally be altered and edited for audio, etc. So I endorse your desire to 'nail it down'. These days are already fleeting.