I remember attending MacWorld Boston in '97, at the age of 12, and seeing a BeOS demo. I was blown away by a demonstration that consisted of a video file playing on the page of a rendered book.

If you clicked the page of the book and dragged it around, it simulated the page turning and the video deforming, without skipping a frame.

I may've only been 12, but that demo has stuck with me since.

Edit: I would love to lay eyes on that demo again if anyone has an idea of where video of it may still exist.