according to Wikipedia - there is no answer so its ok
The single's video was directed by Jamie Thraves, who was hand-picked by the band after they saw several of his experimental short films. It was filmed near Liverpool Street Station in London, and intersperses footage of Radiohead playing the song inside an apartment with scenes of a middle-aged man who lies down in the middle of the pavement. People start to gather, thinking that something must be wrong with the man, and the band are shown looking out the window at the events below. A heated (subtitled) conversation between the man and the crowd develops, as the people start demanding to know what the man is doing and why he is lying there. In subtitles, the man finally gives in and says, "Yes I'll tell you, I'll tell you why I'm lying here... but God forgive me... and God help us all... because you don't know what you ask of me." The camera zooms in on his mouth as the man finally gives the answer, but the subtitles have suddenly stopped, so the reason is not revealed to the viewer. As the camera zooms back out, it shows the pavement covered with the crowd of people, all lying down just like the man. Radiohead members have yet to reveal what specific words the man was intended to have said, if any, and producer Jamie Thraves has said "to tell you would deaden the impact, and would probably make you want to lie down in the road too".