Homemade Ice Cream while camping (with no elect!)

I saw a guy on TV who took two big ziploc bags. In one, he put all the normal ingredients for homemade ice cream (cream, vanilla, etc.) and in the other he put a bunch of ice. Sealed the ice cream bag, put it in the ice bag, sealed the ice bag and tossed it around in his hands (or wrapped in a towel, brr) for about 5-7 minutes. When the ice cream bag was taken out, it had what looked to be real homemade ice cream in it. Cut the corner off the ice cream bag and squeeze it out like soft serve (easiest way to remove from ziploc, also)