Proof people watched the part the brand paid for
A view count says someone opened the video. It doesn't say they sat through the ninety seconds the brand paid for, and that's the question a sponsor actually has.
So we log the exact start and end of the sponsor segment on the deal, then read YouTube's audience retention for that stretch: of the viewers still watching when the segment began, the share still there when it ended. It comes from YouTube Analytics on your own channel, so neither side has to take anyone's word for it.
A strong number there is the best argument for a higher fee next time, and it's yours to keep in your media kit.



