How to make popcorn with a GSM ?

On youtube,

four people phone to four GSM phones that lie around some corn seeds. As a result of the GSM's going off, the seeds turn into popping popcorn. Peter Van De Veire, a popular radiomaker in Flanders Belgium, conducted the same experiment :
but corns stayed corns. Did the radiostation stubru something wrong or are the youtube movies spoofs ? I think they are but I'm not sure. The question is relevant because lot of people will takes those popping popcorns as proof the GSM harm our body. And that conclusion is entirely unscientific.