This is extremely cool!!! Also I find surprising that, as a Spanish speaker with no whistle-spanish training, I was able to understand most of the whistles.
(I should note I haven’t actually managed to watch the video yet, because my audio seems to be broken. Perhaps it would be obvious if only I could hear the whistles…)
Does it happen to you that when you think of a word in English, even if you don't vocalize, some of your vocal cords become tense or move? Well, these whistles feel the same.
Oddly enough, I haven’t ever perceived this, but I can consciously trigger it, and I do think I understand what you mean.