Nikon D5100 autofocus?

I just wanted to know how can I autofocus while recording a video on my Nikon D5100. I've got 3 lenses

18-55mm, 60mm af-s micro 2.8 ED and 55-300mm

I don't think you can. It is manual focus only during video.

Sorry, you can't. I have the D5000. You have to focus before you push to start the video.