Paul Thomas Anderson. As you all probably know Radiohead guitarist Jonny Greenwood has scored Anderson's films like Inherent Vice, The Master and There Will Be Blood.
The song itself built on an emotional piano riff seeps into your head slowly but fully until it carries you away. With the bendy, transient sounds that filter in like a series of thoughts, dreams the effect is like a cascade of memories or visions from the past and the future. Radiohead's ability to transport you like a mind altering musical hallucinogen is strong here. Amazingly the song builds, kind of folds in on itself and builds more and at 5 minutes in it gets even better with some beautiful orchestration.
Daydreaming is the kind of song that will undoubtedly inspire hundreds of film makers and other artists and dare I say, will end up in a future movie as this kind of wonderful piece of emotional soundscape that will only make that unnamed movie better.