Believing in things nobody actually said is of variable difficulty.

But of course screenshots and videos made in OS X are available, especially considering Emacs has been running on that OS since forever. The point of interest here is that it's on an FSF website. Otherwise I don't see why you would even bother to point it out.

1) I'm an Emacs user and enthusiast.

2) I look into a lot of videos about Emacs.

3) I've noticed that, recently, many of these videos and screenshots are by people using OS X.

4) Someone wondered about an OS X video on the Emacs site.

5) I pointed out #3.