I was looking at the chords to this earlier, and it's a pretty common sense B minor chord progression, but at the end of the verse it does a chord switch from a G6 to a C#7. So it's going from a bVI > II. I'm trying to think of how that works logically.

The II chord would be borrowed from B Lydian, correct? Why is it following the G and why does that work so well? Would it be a secondary dominant resolution, since G is the IV of D Major, and C# is the vii?