The debate about whether product video works is less useful than the question of where it goes.
Placement decides whether a video is watched at all, and most stores put video too far down the page to be seen.
Gallery placement gets substantially more views than a separate section below the description.
Published conversion lifts come from vendors measuring self-selected stores, so treat them as a ceiling rather than a forecast.
Video helps where images leave a real question unanswered and does very little where they do not.
In or beside the image gallery, where shoppers are already looking, rather than as a separate section below the description. Gallery placement gets far more views.
The full guide has the formats, the deadlines and the worked examples.