Look up the 1924 public domain arrangement in sheet music form.
Copy those notes into Musescore or an alternative.
Export the notes into MIDI.
Use Pianoteq to play the MIDI file. (It's one of the better sounding virtual instruments out there.) You can export a WAV file from Pianoteq.
Use this WAV file in your documentary on YouTube.
Prepare to get content ID'd by one of the big publishers anyways. You will have to defend the claim with proof that your audio is in the public domain.
I'm not a lawyer, but I happen to know a little about music licensing.