Empathy and my Aspie

I have read a lot of articles and opinions regarding people with AS lately. I think the one thing I am struggling to believe the most is the lack of empathy that is associated with someone with Aspergers. The definition of Empathy is, "the action of understanding, being aware of, being sensitive to, and vicariously experiencing the feelings, thoughts, and experience of another without having these things fully communicated to the individual." I struggle with this "assumption" because though my aspie doesn't always pick up on, or understand why someone is angry or sad, he does however express extreme emotion over a sad movie or a song. So much so that if he feels a movie is becoming too sad (either in dialogue or in the background music they use to create the mood) he will insist, (and sometimes angrily I might add) that his father and I turn the movie off immediately. Same goes for music. If a slower song comes on, it seems to spark sadness in him, and he will demand the song be changed. He has told his father numerous times, "I don't like your country music crap, because it is too sad for me." I also see empathy in him at times in public. If LJ happens to see an elderly person having a hard time or struggling to do something he will say, "mommy, look at so and so, they are making me sad." So, I am left wondering, how can this child, who I am told can not express sympathy or empathy, who can't dinstinguish body language or facial expressions, who can't understand why one would be mad at him for dominating play, or being bossy. How then, can he empathize with perfect strangers, or be so affected by a movie or music? How can they generalize something so big and spread out as AS, and how can they say our children feel nothing?