Sounds like Yorke is singing major 7ths or forming diminished chords with the singing melody. Good luck with that, cover band. Youtube has a bunch of Radiohead music theory breakdowns, what they do is musically complex. The groove is also wonky. It has a kind of funk flavor by emphasizing the first upbeat, but it feels kind of off--like it's lurching. But it pulls you along.
But what I love about it is their ability to find these alien textures that work.