I can't think of a time personally where someone dodged my med unless they were higher level.
One thing I've noticed is that if you run with auto on it runs the same every time. I think a seed number for the rng is given to exp, mountain, challenge, and boss pit instances before you ever atk thereby giving the same crits, dodges, attacks, energy gain etc everytime unless outside forces change it. The only outside force is when white skills are used manually rather than on auto. Once a white skill is NOT used as soon as it's ready it starts to shift the timing of when everything occurs and outcomes can change drastically.
In the video you used med's white at the same time each time which would mean it would work each time if my hypothesis is true.