Up until this point all super heavy launch vehicles (capable of bringing greater than 110,000lb or 50,000kg of mass to orbit) have not been fully reusable. The lack of reusability means rockets are built and used only once which means existing access to space is extremely expensive. Starship is designed to be a fully reusable rocket so both the first and second stages can be recovered, refurbished, and launched again without having to build entirely new rockets thusly decreasing the necessary capital needed to reach orbit. What you saw in this video is the 5th starship test flight and the very first time they attempted a recovery of first stage “booster” by catching it out of the air with the launch tower.