10-4; I don't have this owl hooter, but from the video, it looks like he's putting his top lip "in" the mouth of the call (at least some of his top lip), and then resting it on his bottom lip, and then (obviously) blowing air through it... I have an old Knight & Hale owl hooter that I basically use the same technique with; but, with it, you can give it a lot of air...
Sorry I can't help out more; maybe someone who's got one can better help you out! It sounds fantastic, though!