Not to be insensitive to people with vestibular disorders, but why is this the first I'm hearing about this?
In a nutshell, vestibular disorders are weird and the triggers are subtle. Certain movements won't bother most people, but if you smooth them out, adjust the speed, tweak the effect, things get weird.
I went through an episode of labyrinthitis (an inner ear problem) a few years ago, and it was crazy what would and wouldn't trigger problems. For example, I could watch videos of someone running a dog in agility, but first-person video of any kind was nasty and when that tsunami trashed Japan, I nearly hurled trying to watch footage of the waves on Youtube. I could actually run my dog in agility, spinning and sprinting and and dodging and pretty much anything physical while standing up, but being in a moving vehicle or even just bending over... ugh.