Retention curve

A retention curve plots the percentage of viewers still present at every point in a video, starting at 100% and falling from there. Average view duration compresses all of that into a single number. Two videos with an identical average can behave completely differently: one bleeding viewers evenly across twenty minutes, the other losing half its audience in the opening thirty seconds and then holding everyone who stayed. Read the curve for where the line changes behaviour rather than how high it sits, and compare it against your own videos of similar length, since percentages fall as runtime grows.