Regarding shenfa and the deeper ‘mysterious’ structures and actions, many people can approximate these actions. Many people can watch some videos or spend an hour with a skilled practitioner and make a decent copy of the movements or actions they see. An untrained eye will often easily believe that what they are showing is the real thing, and in some cases that the person is “such a genius” for figuring it out on their own if they are revealed to have not been traditionally trained.
The thing that the untrained observer cannot discern is everything else that the body is supposed to be managing when performing these movements and actions. Essentially we are talking about the structural and methodological rules that traditionally apply.
A good example to use here would be the one of an actually trained gymnast and an untrained astronaut on a space walk. The trained gymnast can perform complicated flips in the air with perfect form. An astronaut who is not trained in gymnastics may be able to perform some of those same complicated flips in a zero gravity situation. To the untrained (or unintelligent) the flips may look similar and they may insist that the two are equally skilled in gymnastic abilities. In this case they are ignoring the fact that the gymnast performs these feats within the limits, and under duress of gravity, while the astronaut has no limits nor such risks.
In terms of gongfu, gravity in this case relates to the connection to the ground and the foundation. If we remove the rules that limit how we are connect to the earth, how our structure must be propped up and controlled, then anyone can move their mid-section around somewhat easily. When the untrained copy-artist has a very loose, or actually no lower body foundation, no rules that limit or conflict with torso movement, then torso movement is easy and may appear impressive.
When the limits are applied that action is much much more difficult, and that is the difference between whether actions are martially useful or not, before we ever begin to consider “energy”.
When people say that internal skill is ‘hidden’ they are usually discussing in reverse. Sure, internal skill can be ‘hidden’ to the untrained eye, but more accurately it is the basics that are hidden while the internal part is somewhat obvious, and more often, fake.