This clever YouTube video will make you think twice about rushing

On first appearances this YouTube video appears to be rather slow and boring. Which, well, we suppose it is if you're not properly paying attention.

However, those who are watching carefully, or who try to fast forward (on desktop at least), may note something quite strange. As well as an occasional flickering, the little thumbnail on YouTube reveals a hidden message.

Overlaid on the main video are a set of stills from a secondary video which shows a car overtaking another and crashing into an oncoming lorry. The work of advertising agency BBDO, the video reveals a message to the viewer: "Don't rush."

Watch below:

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