so a little research suggests Bm as key, I think it is actually D major (the dominant features are D: I-V/7-vi-/7, if we render with Bm as key then it becomes b: bIII-bVII/3-i-/3, which seems to be meandering rather than directed as in the reading in D major) but could be wrong
I get D-A/C#-Bm-C#bass as the rolling progression with sometimes a hint of C#o7 over the C#bass
bass line itself seems to run as D-C#-A-F#-B-F#-A-B-F#-B-C#
sound is a bass guitar with the tone control turned all the way down, maybe doubled with a sine and an organ but unlikely