It's best to go slow, even on YouTube.
BBDO Russia uses the YouTube interface brilliantly for the video below, which purports to show dash-cam footage of a fatal accident. (Such videos are popular on YouTube in Russia.) But in fact, the 10-minute film shows nothing of the kind—just one car passing another.
However, if you fast-forward through the video by moving your cursor along the timeline (as viewers of this kind of material often do, searching for the accident), the preview thumbnails do depict a head-on collision with a truck. Thus, those who "speed" through the film experience an accident, while those who don't speed do not. (The thumbnails also lead to the message "Don't Rush" from the advertiser, insurance company Intouch.)
Clever as hell. Try it for yourself below.