Sharing answers to top q's we’re seeing about the thumbnail experiment: – Custom thumbs aren't going away – 99.7% still see the creator's custom thumbnail – A lot of creators use auto-generated thumbnails, this test helps improve them for those using them: https://goo.gl/A7oDmr
If you have added a button nearby the auto-generated thumbnails that read «Use Better Auto-Generated Thumbnails®» it would have been a lot better for people who actually use auto-generated thumbnails (in my opinion)