yugutou I could not fully understand how the function works from the video alone, but to begin with, Spine can import animations into a skeleton from another skeleton as long as the bone names are the same,, so it is easy to create a template skeleton and use its animations in other skeletons. If you would like to know the details of importing animations, please refer to the Spine User Guide:
The key values for bone transforms are stored relative to the setup pose. If the setup pose is changed, the bone transforms in animation poses will also change. This means that once you have created a template skeleton, you can continue to use the same animation even if you change the position of the bones in the setup pose , e.g. for animating a taller character.