What's the problem? Nikon D3100?

I bought this DSLR around half year ago, and that time just probably wanted to take photographs for college assignments. But for this semester, videography subject was included. Which i found out that everytime i record with my NIKON D3100, its has a lot of NOISE whenever i activated live view or even recording, my setting was:

ISO= 100 (low and still alot noise, really no idea)
aperture = F5.6 (i think this was not affect by the way)
shutter S = 1/50
resolution = 1280 720 30fps / 25fps
and manual exposure, class 10 8gb sd card

so any other problem which i didn't or forgot to change? THE NOISE was so disturb and i really need help for this cause my assignment gonna delay if this doesn't solve

Added (1). Yup, its always activated, i didn't off before, and never

Added (2). Yea… ISO 100 for pretty sure, and i had try 200 or even 400 but its still the same, noise argh…

Did you try activating the noise reduction?

Video you say

Video needs a certain amount of light a certain amount of frames. Are you sure you put the ISO stuck on ISO 100?

maybe in video mode the ISO is not fixed and will rise up to deal with the light situation.

Solution? Get more Light. Seriously with photography you can use longer slower exposures. With video though. You have the light you are getting. If that isn't enough ADD MORE LIGHT

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So Even if you force higher ISO's the noise doesn't gets worse. What kind of lenses do you use.
maybe it has to do with the lens. Not every lens is as smooth in image quality.

It's ISO. The higher you set it, the more noise is evident. Try ISO 100 under the sun.

Everyone is assuming video noise. I case you mean audio noise, shut off the autofocus.