Implement Video Ad Skip Forfeit Reward Screen

Hi guys. We have a game in which we have unity video ads implemented. And we have a reward if they completely watch a video ad. Regardless of it beinng a non skippable rewarded video or a skippable regular video. We want a mix of both. The problem is they get to skip some videos. We know how to give and not give a reward if they skip a video or don't watch all of it...but we want to prompt the user with a screen that says " Do you want to forfeit your prize?" When they click on skip. If they click on skip the video ad should pause and this question should pop up with a yes or no option. If they click on option yes then they can skip and if they press no they can just continue watching video ad and complete it and get their reward. This was implemented in crossy road. Please see screenshot as well. Thanks for all the help in advance!!!!!