Thanks for the reply, 1%.
One reason why I'm asking is that since video cannot be shot RAW like stills can, I usually try have as much post-processing as possible completed before the video compression and the conversion to 8-bit takes place. Fine-tuning things like exposure and picture style parameters. And here I was wondering if it was possible to expand that thought into noise reduction too, not that I have applied noise reduction to videos that much so far, but I was merely curious if it would be beneficial to do so (videos with increased ML digital ISO can get quite noisy). But if you think there's little point in looking into this, I can believe you.
I guess the lower resolution of videos is a consideration in this as well: with less detail to start with, noise reduction can't afford to destroy any more of it, and would have to be very carefully done.
About 6D (not about video NR anymore, though):
It's an interesting looking option, but I'm seeing full frame for less than 2000 € and wondering what's the catch. How does its video quality rank among DSLRs? Severe moire from what I've read, yes, but at least the low-light noise performance should be superior to most other models - maybe even surpassing 5D3 considering a similar sensor with slightly larger pixels?