She used a "kitchen clip." A "kitchen clip" is a tool used to close an open bag. In Japan, you can buy kitchen clips at 100 yen stores, drugstores, and supermarkets.
Sorry for the repeated replies. Please allow me to add an explanation. Kitchen clips are used when you have leftover food after opening a bag of packaged food. Kitchen clips are hard to move when you pinch them, so you can use them like in this video. I think they are very smart and very kind.
