What James Cama showed was long considered secret.
There is another kind of secret in TCMA nobody has alluded to, it comes from having the ability, experience and physical skill to understand something and figure it out yourself.
The secrets the Sifu knows, but can't show you. Wheat and chaff boys. Sifu doesn't appoint a successor, even if he may hand over a business. All the Todai know who's hands are the best at this and that, who has heart, who they look to. Nothing is given, and rarely absolute. The rest is just business.
Also, I can speak for myself and my brothers, we all have secret moves. That's part of the game. Having that little extra bizzo, or a combination you work up. You keep it until someone figures it out, then you make another. Hardly mystical....
Secrets, especially in Hakka or family styles, were to protect the style from defensive strategies. Thus, in part, the issues with teaching Gwai Lo.
I think it is an error to jump to the conclusion that "secrets" are all about money. A secret is worthless if you don't share it, and I've seen what happens when it is wasted, but for the most part, talent and respect are the keys to learning, as with any other pursuit you may undertake where you rely on a teacher.
And of course, as with many things in life, when you reach a certain age and a certain level, you can pick the people you want to associate with, you don't have to deal with every demanding wanker that comes along, or every smart a$$ thinking they got the goods. They may well have, and good on them, they certainly don't need to waste your time. You respect the subject and the teacher will respect you.
Maybe 10 years ago, Sifu told me he has now taught me everything he knows. He wasn't quite right.