Navajo Cradleboard example. Most babies are calm in the cradle board. The tape, flat floor and pillow has the same effect on the Korean kid. And for the record, my mom says she never put me in one. :)
Good idea-baby is supported, swaddled and safe while Mom or Dad can get on with tasks.
Hospitals are swaddling babies from birth, now. They have a special swaddling wrap they send home with newborns It does seem to calm them down. My little grandson seemed to like it.