Does ISO on Nikon D3100 VIDEO even make a difference?

[ehzool]

I don't think it does. Am I going crazy?
This is my first professional camera so I really don't have any clue on this sort of thing.
I took 2 videos in the same lowish kind of light and compared them side by side 100 vs 3200 ISO and there's no difference at all. Am I doing something wrong or is this just how the Nikon D3100 is?

 

[412 Burgh]

Are you on manual settings for your DSLR video? In your settings you have to enable custom settings.

 

[ehzool]

I am in Manual Mode but when I change ISOs and shutter speeds, it shows I'm changing them but there's no difference in video when I play it back.
I have to enable custom settings? I can't seem to find that anywhere.

 

[KmH]

The video mode frame size/frame rate you choose sets the shutter speed.
Actually, in video mode the mechanical camera shutter isn't used. Instead the image sensor is just turned on and off quickly.