They are, but I'ev just rewatched this, and noticed something. I don't want to spoil it for anyone, but
if you watch carefully, there's a camera cut between the moment when they tightrope walk out onto their positions on the handrail, and the moment when they start the high kicks. And with that camera cut, the camera is carefully positioned so it remains below the level of the top of the rail. I'm willing to bet that a thick board was placed there for them to dance on, hidden from the camera by the top of the handrail. It would have been just too dangerous any other way, even with trained acrobatic dancers.
You might very well think that. I couldn't possibly comment.