The sex scene has two stages: first you have freedom of choice over the characters' animation until they become extremely horny. In the second stage a metric bar appears, here you need to get the sequence right to reach the climax and end the scene.
I never get a metric bar?? But when I press the 'A' key, an error page pops up. Also, the game responds very late to my keystrokes. And is it the picture in the middle that I should mimic, or the picture at the top?