They removed the speed and pitch adjuster in QuickTime player, some time in the past decade, I forget when. That was a useful feature to me.

It's not on the site, and I don't care _quite_ enough to figure out how to add it.

That's the problem with built-in software that "does it all" and crowds out the market for other software. One day it might not do it all.

(VLC can do this, but not as simply as I used to be able to).

It is still possible to adjust the speed in QuickTime Player: from .5 to 2x. Not available via Quicklook, but definitely there in the player, either in the menu bar or by clicking the >> in the video window.