Wish I had a computer to look at the video frame by frame... but I don't think there's anything too mysterious happening here...
For those who have ever done a quick change of direction through a slalom or short chicane you might have noticed that it takes very little throttle (or any at all, if the steering rate is so quick?) to lift the front wheel as the bike is coming upright on the change of direction. This is because the steering rate is so great, you have the inertia of the bike coming from lean to upright, the mass of the bike combined with that inertia means that it wants to keep going up - hence lifting the front wheel. If you're then trying to lean the bike over in the other direction while the front wheel is in the air... well you can guess what happens.
I've also seen this with strange geometry/weighting. It was on a work delivery scooter, bit of weight in the top box, a quick-ish u-turn or even just straightening up quickly out of a regular corner would bring the front wheel off the ground and cause a decent tank slapper if not controlled properly.
Given the extremes that MotoGP racers are dealing with it wouldn't surprise me if Vinales front wheel came off the ground and caused him to crash.