For anyone that was recommended this by RU-vid and does not know what is going on, this is from South Korean variety show Running Man. The challenge here was to cross the bridge and finish in order (the numbers on their chest) without falling in the water. What they did not know was they had to draw numbers to know their order to get on the bridge (for example the person who had to be the first to exit the bridge could draw 4th to enter so they had to pass the 3 people in front of them to exit) . Every time the siren went off the next person in order had to get on the bridge. This is what you are watching. Every member had a chance to practice getting over the bridge so at the beginning was Kim Jong Kook, the strongest of the group, practising getting over by going under the bridge as a way to avoid people in front of him still on the bridge. Hope this helps explain what you are watching since RU-vid recently recommended this.
