Noise can be anywhere in low light conditions but if you use some technices you can eliminate it. Try to shoot as close as you can without zooming in. If you are shooting in Manual mode try not to lower exposure because the noise with be added more. If the subject is too dark dont play with exposure too much but use a lighting flash LED Flash for video. If you are shooting in DV mode not HD mode the noise will be seen less. Anyway you can use video reduction software to reduce the noise more.(Check in my blogg for more)