I don't think I really want to use this, though. I'm cautious about what automatic data I allow into Facebook (I'm sure they're already inferring enough from my friends), and while ironically I wouldn't really care if my viewing habits were automatically shared with my friends, I don't really want that data accumulating in Facebook's graph portrait of me.
[edit]
I get that sharing with your friends doesn't happen unless you opt in, but the way it's described, it's not clear if that default state is "all activity is sent to Facebook but not posted to your timeline" or "no activity is sent to Facebook at all."