As the other answers already said, Ⅴ is in fact the standard dominant in the key of f-minor. Speaking in terms of common-practice harmony, it's rather the cm that's the odd one out – a minor Ⅴ chord doesn't really act as a dominant at all, lacking the (classically) all-important leading tone ♯7.
But while we're discussing this song, it's worth mentioning that it does in fact contain a very classical secondary dominant in the verse/bridge: an inverted D♭ augmented sixth chord.
b♭m - fm - D♭+6/B♮ - C
ⅳ - ⅰ - Ⅵ+6/+6 - Ⅴ
(I initially heard it as a diminished seventh chord; was thrown off by the prominent B♮ note in the electric piano)
Both augmented sixth chords and diminished seventh chords are strong dominants, working particularly well as secondaries towards the actual (tonic's) dominant. The b°7 chord shares three notes (b, d, f) with G7, which would be the plain Ⅴ-of-Ⅴ secondary dominant. Additionally, it adds the A♭ note for some extra bite and leading quality. The augmented sixth chord shares only b and f, which may not at first sight point to a G-ish chord, however these shared notes are the tritone, the heart of the dominant's leading character.
Note that D♭+6 is enharmonically equivalent to D♭7, i.e. the standard dominant G7 shifted down by a tritone (thus the description “tritone substitution”, which is what this would be called in jazz).