If its a DVD of her and trump having sex, I don't think people would really care, but it would totally destroy trump in public as it would be ANOTHER LIE he told....it also would call into question how she came to possess such a DVD since I would assume trump is not stupid enough to go to HER place...
But you never know 
I don't see it as having much impact. Sure, the 1st 3 days, it would be all over the news... but within a week, no one would care. Far from destroying him. Remember, as long as he can stay, white, male, and straight in his supporters eyes and keep on about the wall, nothing short of maybe child or gay porn would throw him off track.