I don't think average watch time is a particularly useful metric, because no matter how they count views, there's some kind of arbitrary cutoff. If they count a

I don't think average watch time is a particularly useful metric, because no matter how they count views, there's some kind of arbitrary cutoff. If they count a view as soon as the player finishes loading, they'll include a whole bunch of people who didn't intend to watch the video, and in fact only "watched" a few milliseconds of it before bouncing. So that will drag the metric down artificially. I bet if they count views as soon as the video starts playing, they could drag down average watch time by improving player load time, because they'd count more unintentional "views" of very short duration. I hope/assume this is part of a suite of metrics that they provide to advertisers, so you can understand it in the context of other things like video completion rate or counts of views that reach X% through the video.