i use virtualdub a lot, and have often combine several filters to remove noice from video.
Look for virtualdub filter noice some there are several smoothing and edge perserving filters.
As well as time delay based smooth filters (there the previous #frame tip comes in handy).
here a link with some good free filters : http://www.foxtoo.com/Windows/download-MSU-Denoiser-VirtualDub-plugin-10135594.htm
Notice also for compositor there exist some pre smoothing node setups
And i red that AS sampler has been improved to better remove fireflies, possibly low noice too (not sure), but i have not yet seen a compiled downloadable link yet
Sometimes even adjusting codec bitrate can remove noice (noice is data that doesnt match most of the image and can get lost by compress/decompress), but thats a bit fine art of tuning video codecs, its not easy, only practice to learn, there are no rules for it.