@tonfilm thanks ! I was missing this setting… I was sure that I did change it before, but it made no change at all. In the middle I reinstall the Magwell capture card downloading the drivers from their site, still, the driver don’t find the capture card, but I did use the inf, maybe that made it work ? not sure, but thanks to your suggestion the change was immediate, as soon as I change it to RGB the lines were on the same shape but different levels.
So I check all the Nvidia settings, and I found that some settings were a little bit off the default, 0,49 or 0,99 , I center all the sliders and it seems to work quite well now!
on the mid, max and minimum levels of that Dynamic Texture ( to avoid getting some other result due to video codecs ) It seems to be exact
Playing some videos / still pictures I do see some minimum variance on some parts of the graph, but I do not see any difference on my monitor ( I do not have a trained eye or experience on this topic but hey, I feel Spilberg now :D )
Here are all the results and the settings I use, I hope this help someone in the future