"In the universe there is an immeasurable, indescribable force which shamans call intent, and absolutely everything that exists in the entire cosmos is attached to intent by a connecting link."
I've seen the Castenada books. Weird stuff. You know, they also talk about "tendon energy." Castenada asks his teacher why they use the term "tendon," wondering if it is the wrong translation, since they talk about areas like the abdomen which are not big on tendons (compared to the limb joints for instance). He doesn't get a very good answer except that yes, that is the right translation.
The quote you provided is pretty big-picturesque and metaphysical, but I think there is a connection from that point of view. Intent controls ki, and ki makes connections between things. Metaphysical musings don't help your training though. There is a much more practical level to deal with, unless we are posting in the "spiritual" section maybe. And I can't talk about the degree to which any such practical side of the Castenada stuff is relevant.
Regarding demonstrations, I'm workin on it! But Ikeda sensei does great demonstrations. As a matter of intro to these videos, I'd like to point out that visualizations of forces, like "imagine water is shooting out of your arm like it is a water hose," or "imagine you are sitting on an inflated balloon" are simply tricks/tools to control intent in a large-scale way. There's no real difference between those types of visualizations and what happens when you "go to reach for a cup but abort the action right before you do it."
Here, Ikeda sensei
uses the visualization of playing catch (i.e. intent) to control his body (and his body's connection to his partner) so that his partner falls down. It's something that makes uke move without forcing him against the directions in which he is strong.
Here, he points out
that the state of your intent in your core/body is the key to doing another similar type of kuzushi effect, against even more resistant ukes. He explicitly points out that fighting against their strength is different (and less effective) than using this intent-based trick. ("Right place" is the visualization here, rather than playing catch.)