Engagement seems a pretty blunt metric for this. Especially since Youtube has a near monopoly on user generated video content. A user would have to be mightily

Engagement seems a pretty blunt metric for this. Especially since Youtube has a near monopoly on user generated video content. A user would have to be mightily perturbed to abandon their favorite content altogether over poor video quality. I bet most of those 90% of people who stuck with 480p don't even know they can manually set the resolution.