Percentile pooling summarizes a clip by reporting a low percentile of the per-frame score distribution instead of the average, so the worst moments are not averaged away. The 5th-percentile score (perc5) is the value below which the worst 5 percent of frames fall, and the 10th-percentile (perc10) covers the worst 10 percent. For a clip whose worst second is also its worst 10 percent of frames, both perc5 and perc10 report that bad value directly, telling you the truth the arithmetic mean hid; it is the closest single number to how bad quality gets for a noticeable stretch. This makes it the statistic a quality gate in CI/CD should watch, because it catches a regression that a mean would wave through. The trade-offs are that you must justify the cutoff you pick, and that the percentile says how bad it gets but not how often. It sits among the temporal pooling toolbox beside the arithmetic mean, the harmonic mean, the median, and the minimum.
