I'd say it's an unverified observation. So it's not a fact.
For example, my father-in-law was jogging with his wife. She tripped and fell to the ground but wasn't hurt. He swears that she floated to the ground. That God caught her and set her down gently. I suggested to him that his perception might be flawed. Perhaps in his panic things appeared to run in slow motion. Sometimes it's difficult to properly perceive time. Perhaps she didn't feel pain because her brain was full of endorphins. This is called a runner's high. My father-in-law was greatly offended and claimed it was a fact she floated to the ground. But claiming it is fact doesn't make it so. An unverified observation is not a fact.
Does that mean he's wrong... she didn't float to the ground? I highly doubt that she did since that would defy the law of gravity. It's a trillion times more likely that his perception was in error. But my point isn't so much whether it happened or not. My point is that it is not a fact that it happened.
One more point, my mother-in-law says she floated too. So is that confirmation? No. What is needed to verify this observation is an actual video (not doctored) and stop watch.
Comparing apples to oranges BR. In your scenario I take your side but in my scenario if a dust devil came by and the water disappeared it's gone and someone telling me about it would be proof enough. If someone wanted to concoct a story it would be a hell of a lot more complex than that.
That said, I understand your argument. A good example would be Environment Canada. When tornadoes are reported in Canada they always say something to the effect that it's alleged and more info / proof is required. Well from my way of thinking if buildings, trees and other structures are destroyed it's more than a fart in a windstorm that caused 'em and I don't need video proof to believe it. Seems the " smart " ones do though.