Uzi said
@ratvn Sounds pretty reasonable except this:

So in the tune, it's not in Bm since there is no A#, nor Em as there is no D# either. 

There is no A# in Bm and no D# in Em.

For example, the Bm (natural minor/Aolian) contains all of the same notes as DMaj:

B C# D E F# G A 

For Em:

E F G# A B C D, which is probably correct (except all the C's in the song are C# i. e. augmented 6th). 

I'm not making any judgements about what the "right" answer is, it's just something I observed and wondered about the reasoning behind it.  

PS:

According to Chordify these are the chords: chordify.net

@Uzi, you're correct and your points are well made. I made a mistake there, or rather not complete, my bad. And yes, we're having these discussion to learn as I'm a beginner and would love to learn from you all.

''So in the tune, it's not in Bm since there is no A#, nor Em as there is no D# either. 

There is no A# in Bm and no D# in Em''.

Yes, you're absolutely right that there is no A# in "natural" Bm, and no D# in "natural" Em, but there is in "harmonic" Bm and Em.

So I stand corrected that the sentence should be "it's not in harmonic Bm since there is no A#, nor harmonic Em as there is no D#". Sorry, my bad.

Here is some from wikipedia, http://en.wikipedia.org/wiki/E_minor

E minor (Em, Mim) is a minor scale based on the note E. The E natural minor scale ( ♭ ♭♭) consists of the pitches E, F♯, G, A, B, C, and D. The E harmonic minor scale ( ♭ ♭ ) contains the natural 7, D♯, rather than the flatted 7, D – to align with the major dominant chord, B7 (B D♯ F♯ A).

And http://en.wikipedia.org/wiki/B_minor

B minor is a minor scale consisting of the pitches B, C♯, D, E, F♯, G, and A. Its key signature consists of two sharps. The harmonic minor raises the note A to A♯. Changes needed for the melodic and harmonic versions of the scale are written with accidentals as necessary.

And the reason behind the switching from "natural" minor to "harmonic" minor is from the provided link from my previous post, here is an excerpt:

"http://www.guitar-chords.org.uk/chord-theory/minor-key-theory.html

Generally speaking, the cadence is what reinforces the home key and mostly refers to the V-I transition in a chord progression. In the major scale, the last note is one semitone below the root and it's called the leading tone, as the name suggests, it leads nicely into the tonic (root note). In the key of C major it is the B note. The "five chord" in a major key contains this leading tone and has a strong pull back to the tonic. This strengthens and highlights the key. In the key of C, the G sounds like it wants to resolve back to C. If we make the five chord dominant (G7) then this "pull" becomes even stronger.

The leading tone in the natural minor scale however is a whole tone below the root and it doesn't have such a strong pull. For composers this makes it a bit harder to really establish the key. The five chord in a minor key doesn't have the same effect as it does in a major key because the leading tone is not as close to the tonic. You can easily try this yourself. Play a i iv v progression in the key of A minor. The chords are Amin Dmin and Emin. The five chord (Emin) sounds Ok and resolves reasonably well back to the A minor but it's still fairly weak sounding.

Harmonic minor

The solution to improving this weaker sounding cadence in minor keys is to raise the leading tone of the natural minor by a half step which results in a stronger pull back to the tonic. Using A natural minor as an example, this would mean making the G become G# which in turn will make the E minor chord, or the V chord, become E major. This raised seventh gives us a new scale formula 1 2 b3 4 5 b6 7 and we call it the harmonic minor scale.
For an example, a very common minor chord progression is the i - bVII - bVI - V. In the key of A minor you might recognise these chords used in many songs, A min, G maj, F maj, E maj. This chord progression is all in natural minor except for the V chord (E maj) which temporarily switched to harmonic minor for the V-i cadence. If you were to solo or create melodies for this progression then you would use the harmonic minor scale over the E chord and natural minor for the rest."

We like to talk about chord progression for the mentioned tune. Let's take the first 2 measures:

BGE F#E|BGE F#GA

The tune sits on the B minor scale, starts with a B so sticking in a Bm chord (B D F#) makes sense, however, second note of the melody, G would clash with Bm F# note as it's minor second interval, likewise, the third note, E, would clash with either D or F# (major second). So for my choice, an Em chord (E G B) seems to fit better. What do you think?

Further more, the chord progression for the two bars could be Em Bm Em D, or Em D Em D. i-v i-VII or i-VII i-VII, (E Dorian tonic swinging back to the root of the major scale in which it sits) which I think fit the E Dorian scheme better than a B minor.

What do you think? Awaiting for correction.

Thanks