I'm a bigger fan of just de-noising video, and leaving it gone. I don't want it replicated, UNLESS the de-noised video is such a low-bitrate blocky mess that you absolutely NEED the noise in the video to hide it.

Conan The Barbarian DVD is the noisiest film I can think of off-the-top. Strong de-noising makes it look far, far better. But just about every movie out there benefits from modest de-noising.