I think that, concerning paid users, what they would be interested in would just be daily/weekly/monthly paying users. As for minutes watched they'd be incentiv

I think that, concerning paid users, what they would be interested in would just be daily/weekly/monthly paying users. As for minutes watched they'd be incentivized to reduce it as far as it is possible while still retaining a paying user. After all, they don't show more ads if a paying user watches more minutes of video. At least not yet.