Björk always struck me as being kind of too dark for Alpha, moreso her music videos than her music, so perhaps it's just whoever she has directing & producing the music videos? Not as solid on this though, as Benn Jordan writes some very dark music due to the bipolar depression, but is probably SEI, or some kind of Delta NF.

Moloko, perhaps solely through Roisin Murphy (who is about as IEI as they come), would be Beta definitely.