meta-video 是做什么的？
Meta video ad performance audit for Reels, Stories, and in-stream placements. Evaluates hook rate (3-second view rate), hold rate, ThruPlay rate, average watch-time percentage, and the retention drop-off curve, plus sound-on/caption compliance and safe-zone spec compliance. Distinct from meta-creative's diversity/fatigue scoring — this is video-mechanics performance, not concept diversity. Use when user says video ad performance, hook rate, retention rate, watch time, ThruPlay, drop-off curve, R