Excuse my lack of proper theory throughout this post.
Seems to me like it's just well chosen modulations.
The beginning of the piece is in B minor (hints of B dorian) for the most part and then at 48 secs he plays C major/major 7th which is where the modulation takes place (because that chord wouldn't normally work in B minor, being rooted on the flat 2nd), moving into a sort of VI-VII-I progression with the I being a E major chord instead of a E minor chord. You can tell because of the commonly used sus4 to major chord thing/suspension (I have no idea what it's called) on chord I. Then another modulation takes him briefly into B major before going into the VI-VII-I progression again before subtly modulating back into B minor.
The choice of modulations is superb and subtle basically, with the notes in the melody almost naturally leading into the modulations. I've been trying to incorporate this a bit more into my music but as you can tell from my (lack of) theory, it's been tough!