It helps to have the right timing since there is that moment of suspension.. least that's how I see it.
Shortening stirrups.. I don't think that would help. It might, but if it's what I think it is..
OP, do your thighs and seat stay solid and fluid with the canter motion? Or do they come out of the saddle?
The audio of the video is for the canter depart, but look at her leg. See how her leg is? She's not pushing into that stirrup, she's just resting it on her toe. It's her leg that is stretching down, and you can see when she squeezes, her leg is the only thing that moves.
Just make sure you aren't pinching with your knee or grasping with your thigh, relax down and forward into the motion. Curling up = when problems start to happen.
I hope I've been helpful.