Where's the light?

I've been trying to teach Barrett to point...or at least look in the directions of particular objects. So far, we've learned light. He doesn't say, "light", but anytime I mention a word, he looks directly at the light.
Now sometimes, he has little conversations with the light. I don't know if he is talking to the light, or about it.
All I've managed to capture is a picture. When I turn on the video camera, he quits talking as much. I'll catch him in the act sooner or later.