Hook rate

Short-form feeds hand every video the same test. The viewer is already watching, and decides within moments whether to stay. Hook rate measures how often they stay, and YouTube reports its own version as viewed versus swiped away, which does for a Short roughly what click-through rate does for a long-form video. The opening carries the same weight whether the Short runs 15 seconds or 60, so length is rarely the culprit. A weak number is pointing at the first frame and the first line, and no amount of work further down will move it.