Nikon D5100 Video Mode?

Okay So I'm a 14 year old girl. For my birthday my father bought me a Nikon D5100.It's great I really like it. The thing is I'm not a photographer and I'm new at things like this. So when I take videos and I want my camera to focus it makes this weird noise. All of the Nikon D5100 do this noise while focusing in video mode, but I want to know if there's any other lens that can minimize this noise? Or maybe a accessory.

Look for the AF-S setting, if your lens support Silent Wave Motor focusing, you can find a list of supported lenes here.http://amzn.to/GYBHYC