Yes technology has improved, but I gather from your other posts that you're making a DVD. You should continue in your own thread instead of hijacking others, because there is relevant information you have omitted Adding CUP(6) for example during postprocessing can help. Has this changed? Is it possible to eliminate noise in video without blocky artifacts from forming during encoding? Or rather, is there a special script that can be composed in Avisynth that can prevent this? I know this post is old as I'm sure the technology has changed a bit from 5 years ago.
UNLESS- if you do NOT see it when you preview your capture on pc monitor, then it might be something else and I would have no idea. The noise on the bottom is hard to see in your attached image, but I think it is ordinary head-switching noise, you don't see in on TV viewing because it falls into the "overscan" region, and is only seen when you view on a PC monitor. It might soften your video more than you like, though. I'm surprised no one mentions Convolution3d. I don't care how slow, I'm happiest with this one so far of all I have tried. If you use the setting to denoise all 4 planes (Y,U,V,Luma) with a single parameter setting, it is quite fast, but if you have different parameters for each, it is deadly sloooowwwww. I second the vote for FFT3d, it's doing a really good job on my current project. You'll have to check the documentation for the particular filter you are using. Some of them have the default set to Interlaced = false, so they won't work properly on interlaced material until you change the default parameter. With many of the aviSynth filters, you must specify a parameter for Interlaced = true or = false.