"In essence, the accuracy is entirely dependent on the difficulty of the test."
AKA doesn't work for shit. Don't bother with it. And even if it did work, it'll be an arms race and right now the deepfakes have the nuke and Intel has a musket.
those super embarrassing things you did at that party were obviously a deepfake by a angry neighbor or jilted lover. Dumb things politicians say, deepfake smear campaigns, all of them. Those politicians all have IQ of a 180 or how would they have gotten into Congress and the White House etc.