When i listen to music i really love with the lights closed and nothing else that can distract me(i must have no doubts nobody can see me) i can ''get into the music'' pretty easily, it's kind of scary but let me try to explain you... my body moves by it self, i may even look epileptic but i feel the music and vibrate to it, my closed eyes turn around until it hurts(can't control them when the music is too good) it's a great experience and i also see things that i could not describe, new colors.... i travel in space... i really can't explain it. but i don't see the people playing the music, i see the music itself(you can't understand until you succeed) this probably first happened to me listening to Camel's Mirage which is still one of my favorite albums. It also happens easily with Pink Floyd's Echoes and such, Gentle Giant and with Al Di Meola's Land of the Midnight Sun(Album).