How to shoot video in very low light situations with Nikon D3100?

I've been trying my hand at using the video mode on my camera but I'm not sure how to change the settings to shoot in low light situations, any help?

Added (1). Thanks for the reply, I know I may have to shoot with a high ISO, but I don't know how to adjust for the video mode. Any help?

You will have to use high ISO settings.

What you may not know is that production companies use a lot of supplementary lighting to provide enough light to shoot video and it is used to simulate low light, but is not

You can try using HIGH ISO's and fast lenses to see what happens, but in the end, you may have to use a lot of incandescent lighting set ups

The problem is that with most dslr cameras video sets everything to full auto so you won't be able to control anything but the focus - turn the lens to MF.

Low light is always a challenge. I have pretty good luck grabbing focus on a bright spot in the room.
If there's a candle burning or have one of the folks in the shot shine a flash light on an object, focus
and roll - that's about all you can do except for adding light.