"This film was made as an historical document to record permanently and accurately the trial of the Nazi defendants at Nuremberg. It consists of footage from German films documenting Nazi personalities and activities interwoven with film shot during the trials -- including testimony and statements from defendants, prosecuting attorneys, judges, and witnesses. It follows the story of the rise and fall of Nazism from the putsch in a Munich beer hall to the Nuremberg trials, and contains flashbacks of a variety of Nazi crimes against humanity. This particular version was made for German audiences
You can stream Nuremberg, Army Television Release Version, 1950 (1950) free and legally on OldReel, via the Internet Archive.
Yes — it is in the public domain and can be watched and shared freely.