That's what I thought as well, but watching some other videos on their site, they say the boost happens in "the last second" https://youtu.be/xYYTuZCjZcE?t=2m34s. Any sign of thrust before landing really isn't visible in that video either. So unless they've never actually fired it successfully and we just don't know what it looks like, it's possible that it's just so close to touchdown that we can't distinguish the thrust from the landing.
I'm assuming that decelerating by 13mph over < 1s is still quite a bit better than by 15mph instantly? But I really don't know.
I'm assuming that decelerating by 13mph over < 1s is still quite a bit better than by 15mph instantly? But I really don't know.