I imagine it would be similar to Youtube's model. >A view is counted when someone watches 30 seconds of your video ad (or the duration if it's shorter than 30

I imagine it would be similar to Youtube's model. >A view is counted when someone watches 30 seconds of your video ad (or the duration if it's shorter than 30 seconds) or interacts with the ad, whichever comes first. https://support.google.com/adwords/answer/2472735 https://support.google.com/adwords/answer/2472735