The capture software records what’s on your screen verbatim. Assuming your CPU isn’t a potato it’s almost unheard of now for that software to introduce stutters etc.
You have a CPU that is perfectly capable of capturing video in 4K and playing the game at the same time so I’m absolutely confident that what we’re seeing in that video is what you see on your screen, and what I’m seeing is far removed from ‘buttery smooth’.
That’s no surprise however, because there isn’t a system out there that can run this game in 4K / Ultra / TAA with LODs of 400/900 at anything approaching a decent frame rate. The game is simply too demanding of CPUs to do that (unless you’re flying a light aircraft far away from any ‘life’), which I’m sure is one of the reasons we’re getting FS ‘24.