Interesting clip.....one would have to assume an intelligence beyond that of the pongid apes, simply by their covert existence. Then there's the evidence for structured language, as well as cooperative behaviors, although these could be expected from most contemporary hominid forms.
Some have conjectured that with the lack of technological advancement, they, as a branch of humanity, focused on the development of "other skillls" this could include the refinement in the uses of various frequencies of in freely and how to produce and project specific frequencies for specific effect within those they use it with along with possible long range communication. Of course this might also be extended to include the various "woo factors"
Their capacity for strategic actions seems pretty amazing