Hi Peter, thanks for posting this interesting link. There are certainly similarities to Greg’s views as I understand them from where I’ve got to in the WindWorks course, but there do seem to be some differences too, though perhaps these are rather nuanced. In particular:
Air speed: Although the video you’ve linked to is mainly about aperture control, Jason does mention air speed as another factor in pitch change. As far as I can recall, Greg doesn’t mention anything at all about air speed anywhere in the course up to the Moderato stage (where I’m up to). What Greg talks about mainly is ‘shape’, which I take to include aperture control, but also other internal changes in the mouth such as tongue position.
How to aperture is controlled: In Jason’s video, the aperture is conceived as a ring of lip tissue through which air passes, and Jason appears to conceive of controlling the size of this aperture by contracting a ring of muscles surrounding the opening, both at the sides and on top. If we think this way about aperture control, we might (conceivably) think that we need to contract the aperture in a vertical dimension as well as in a horizontal direction. Greg doesn’t want us “clamping down” in any way, so it seems to me his emphasis is on contracting the aperture in a horizontal direction only.
These are relatively subtle differences perhaps. And I’m certainly no expert in any of this. Maybe someone who actually is could chip in?