The video shows a group of friends aiming four cellphones at unpopped kernels of popcorn. After they dial the phones simultaneously, the kernels suddenly start popping.

The videos, shown in different languages, have been watched by millions and scared many about the heat generated by their cellphones. But the truth is, cellphones can’t pop popcorn.

The videos are a viral marketing campaign by Cardo, the maker of Bluetooth headsets, as my colleague David Pogue wrote in this post last week. The campaign has clearly caused alarm; several readers of the Well blog have recently submitted links to the videos as evidence that cellphones are a health hazard. Since fessing up to the campaign, Cardo has added its name to the videos.

It’s not the first time someone has alleged that cellphones produce enough heat to cook food. The myth-busting Web site Snopes explains here how an egg-cooking rumor started with a magazine spoof. Read here about how my colleague Paul Adams tried the experiment himself.