Thought experiment: Which would transmit info faster, a beam of light or a tube of balls?

Ok, this has been stuck in my mind for a while.

Lets say that you have a laser and a long tube filled with ball bearings. You are at one end of the tube and a friend is at the other end, which happens to be quite a distance away, more than a light minute. lets say that there is no other variables: the balls are touching one another and the entire tube is full, no empty space.

The laser is set up to be powerful enough for your friend to be able to see it, and the line of sight follows parallel to the tube and is in a perfect vacuum. The emission point is right at the start of the tube and the target is right at the end of the tube.

Now at the same time, you turn on the laser and push one more ball bearing into the tube, pushing the last ball out of the tube at the other end...

Which would your friend see happen first? The laser dot, the ball come out of the tube, or both at once. Disregard human reaction times and assume that he can see both at the same time. Like I said in the subject line, its a thought experiment.

Actual explanation of your answer = bonus points :)