I guess it makes sense for this particular ad, that you don’t get anything if the user cancels the video. The incentive would be that it’s a give and take. The user is MORE likely to watch the entire video, because otherwise… they won’t get a reward. I know that I’ve personally downloaded a few of the games I’ve seen, even while I was testing this app, because so of them do look appealing! So you might even get more clicks on this type of ad, than you would on a standard banner ad. (That’s just a theory)
I would suggest though: having BOTH ad types in your app.
This way you can reward the user, by watching an ad that is out of the way of the design, but also continuously generate impressions and potential clicks with a banner ad.