In general you need a greyscale noise generator,
followed by some blur (like SmoothKit Gaussian, the amount of blur will change the size of the video noise),
followed by some color correction that restrech out the black and white. That gives you moving video like noise.
and then if you want video snow then you need to blend that into your image
I think DigiEffects has a product called Damage that has such receipe built-in for that.