It showcases BTS' massive free show at Busan's World Expo in October, which welcomed more than 50,000 in-person guests.It showcases BTS' massive free show at Busan's World Expo in October, which welcomed more than 50,000 in-person guests.It showcases BTS' massive free show at Busan's World Expo in October, which welcomed more than 50,000 in-person guests.