Yes all very interesting. I originally saw it as a ii V I VI variation (as someone noted) but now going with the Dm tonality, i could argue the Bdim is actually Dm6. (Assuming its half dim) But again all in that 4 bar riff, not time in a bottle.Yeah, all triggered by a typo in a chord chart (wasn't just me that was confused, though, their pop-up chord symbol thingie also read it as B Diminished). Curious, but interesting discussion for an accident, thanks, folks!

(Their "Red" era 70s incarnation had a particular fixation on the tritone.) But yeah, it's the driving tension it gives to the flow that I like.