I haven't found the "answer" yet for offhand, lol.
My body type doesn't work well for offhand or kneeling but especially kneeling, I'm not flexible, less than anyone I've met. Even though I use many of the techniques as the guy does in the video, no matter what I try I'm not remotely comfortable which makes me wobbly or torqued in some direction. I remember when I was lifting weights with my son for a couple years that really helped for my offhand, even my heavy rifle was easy to hold up back then so strength made up for other deficiencies.
I know when I try "really hard" not to settle for an "ALMOST" that I score higher. That can mean I'll have to put the gun down for 20 seconds or so then try again, and maybe a couple times. I also try if possible to aim for something I see near the middle of the KZ, like a splat or shiny spot for example. Though sometimes I'm in the proper mood and sometimes not, what I mean by that is that its a better mental state when for whatever reason am knocking them down most of the time??!! I prefer to dial the magnification down to 12x or so as well.
Practice makes a huge difference if I'm able to discipline myself which has always been another problem, lol!