Howdy people!

I'm looking for a little help on a song by a Danish band called Figurines. You can see/hear the song in the youtube clip:


I'm mostly interested in the rhythm part played by the singer. I can't seem to figure out what type of chords he's playing, or if it's a modified tuning. The base goes D-Db-F-B but I just can't replica the sound with regular chords in stardard tuning.

Any help would be appreciated. Thanks.