Why did you start in the middle? The spring bones is near the end. 21:25
But yes, SkeletonUtilityBone will do the trick, and it's up to you what Transform-controlling solution you want to use.
It could be Box2D or 3D physics or whatever he's using in the demo (not sure if it's bundled with Anima2D).
You could also opt not to use SkeletonUtility at all if the underlying system makes more sense that way. Since you do have access to Spine bones directly, just do what SkeletonUtility does, but without the extra stuff.
The SkeletonUtilityAnimatedPhysics sample scene was an early sample of this.