No the nvidia setting to vertical sync to "on" is to prevent stutter. Videoclock is also to improve motion too. It is not either way. But I Am no expert, but I have never read that these two features are two different ways. The nvidia setting is a must for many or all using JRiver.
I myself do not use videoclock, but always do the nvidia setting above. Also this new feature; Present Queue...I experience better motion and more stability in motion handling in day to day movie rendering, also less artifacts too. I stay on sdr as this is best for motion, but hdr is significantly better with this new feature too. If I on rare occations use hdr..I always turn off tonemapping as this introduces artifacts on my lg b1 oled. (Newer LGs or Sonys may not have any problem, as I read that interpolation on newer tvs sets have improved quite a bit.)
Update!
I just read this on doom9 from a jriver user(manni). He writes that on nv driver 572.16 he does not need vsync set to on in np. Also if you where to use videoclock, its advised to set display auto changer to auto (just read this in their wiki on their videoclock feature).
as for mannis findings I paste his comment below:
"It also looks like, at least with JRiver, it's not necessary to set vsync on in nv panel in order to avoid unreported frame drops. I've only played a short bit of my test clip (Pacific Rim) and I couldn't see any unreported frame drops. With previous drivers, it was obvious and frequent.
If this isn't confirmed, it would be great if JRiver allowed to specify if we want vsync enabled or not, that way we could leave "Use the 3D App setting" option in NV panel.
I only had to disable Gsync, as always. Normal power seems to be working fine too (but that was the case already with previous versions)."