There are four pandas visible in the footage uploaded by YouTube user mrpenta, but the Chengdu Research Base of Giant Panda Breeding in Sichuan, China, actually currently houses and cares for over 100.
The research base was established in 1987 to further understand and protect a struggling population under stress from dwindling natural habitats and the ever-present threat of extinction. Although according to its website the base adheres to a strict no wild capture rule, it has contributed significantly to the remaining population of pandas through its successful breeding program.
The program has made possible the births of many impossibly cute cubs, including those seen playing with their keeper in the video. And by the way -- being chased by tiny panda cubs down a hillside? It's the one game of tag we would love to lose.