I've head some NWS Severe Weather training and I know that tornados are totally not predictable. There can be 150Kph winds on the ground and almost calm at 25M up- or there can be several hundred Kph winds a half kilometer is every direction- up, down, rotating, rolling, with attached vortices going in several directions at once. And it can change from one to the other over a dozen seconds. "Rope" tornados like in the Vid shown usually don't have high winds far from the funnel itself, only very close to it. Usually- not always.
The flying in the vid might be possible but I would neither believe it nor would I want to be anywhere near any pilot that far removed from sensibility. Even ground-'based tornado chasers spook me. I've been through the edges of two small ones (both EF-1) and a Derecho event and I don't want to be that close ever again.