That's an okay, but incomplete explanation of "ground force." He correctly implies that it's a process that is not sequential or comprised of individual body movements, but doesn't explain how the body is connected from the point of contact to the ground and back, or how it is a cyclical process, driven by the manipulation of one's own internal tissues and structure -- not just the input provided by the partner's force when he pushes.
For someone with no prior internal training, the video is probably a little confusing and leaves lots of questions, but it does touch on a few of the principles involved.
Cady Goldfield