it sounds quite simple to me. there is an ambient type sound that accompanies the piano that fades in slowly, leading up to the part you reference. then it becomes more prominent... it has a slow LFO assigned to the pitch. this sound has a lot of delay on it as well.
then, when it's being played, he is maybe pitch bending it a little bit with the pitch wheel...or enhancing that LFO's effect on the pitch by using the mod wheel (assuming the mod wheel is assigned to the previously mentioned LFO) but basically the pitch is being modulated on the pad, somehow...the volume of the pad is also fluctuating throughout the song.
on a synth, this sound will have a slow attack, somewhat of a long release...sounds like sine waves to me with pitch shifts assigned on the envelope.
...also sounds like a digital synth or vst.
the piano parts and sounds almost immediately reminded me of Clint Mansell.