Very interesting piece. Distant harmonies, I've seen those used a lot for emotional quality and modulation, especially from Chopin onwards, but even Beethoven does it. I hear these keys in the piece:
F minor
C minor
Bb minor
C# minor
A major(brief glimpses)
Eb major towards 5:00
Ab major
E major(brief glimpses)
B minor or F# minor, not sure which
F major towards the end
And if I were to relate all these back to F minor, this is what I would get:
Tonic
Minor Dominant
Subdominant
#v Chromatic mediant
#III Chromatic mediant
Subtonic(could also be viewed as the Relative major of the Minor Dominant)
Relative major
#VII
Minor tritone axis or #i
Parallel major
Only about half of what I hear harmonically is in any way closely related to F minor and the rest is at a minimum chromatic mediant distant and at a maximum tritone axis distant. I have used this tritone axis relation before to go from sharps to flats quickly while staying in minor. My March of Iwo Jima piece uses this exact relation in its development section where I go from a somber F# minor that develops the second theme via canon to an intense C minor that builds the motive of the first theme into a full orchestral fortissimo in the space of a single diminished seventh harmony, because viiĀ°7 of F# minor and viiĀ°7 of C minor are enharmonically equivalent.