Thank you,
JF!
Yeah, it's a really great chord (C with the Bb bass), technically it's a C7, but sounds magnificent! You can also find it in songs 'Eclipse' by Pink Floyd or in 'Thank You' by Led Zeppelin among others.
I'm not sure about the Dsus2 chord, you seems to play Am instead ?
Same for D5, to me it sounds like normal Dm. Why D5?
Yes, my ears tells me it's a normal Am and normal Dm. I think the guy, who wrote this tab, just thinked that it would sound better without F in this Dm chord. Normal Am also appears in the beginning (3d chord). With Am7 it sounds too jazzy.
Well, and chord in the very end of the song is properly called Fm6, not D5b5.
P.S. In that particular take I've messed up beautiful D7/Ab chord at 3:39 a little bit. But I'm 100% confident in it, as well as in whole song chords.