The Victory of Faith (1933) is the first documentary film directed by Leni Riefenstahl. It documents the Fifth NSDAP Nuremberg Congress shortly after the party came to power The film includes Ernst Röhm, head of the SA and, at the time, the second most powerful man within the Nazi Party. Less than a year later, Röhm attempted, along with other top SA members, a military coup against the elected government of Hitler. The film Triumph des Willens was produced to replace this one and follows a similar script.
You can stream The Victory of Faith(Sieg Des Glaubens) free and legally on OldReel, via the Internet Archive.
Yes — it is in the public domain and can be watched and shared freely.