Sorry, I cannot explain smooth scrolling better than that: When you put a page in motion, it won't stop right after you stop scrolling, but keep scrolling for a while (like due to inertia). I can't find better English words for that.
Completely, totally brain-dead idea. Sucks big time. In every app.
Curt, I think what you describe is called auto-scrolling. I don't like it either, but other than with smooth scrolling, I can see some usefulness in it.