Putting Video ads in app to make money?

Hello so i have an app in which i would like to have users watch an ad/video ad or what ever kind of ad generates most money in exchange for a "special code" they can use in the app. I thought about using linkvertise but i dont know if i can generate unlimited links with that since each user would have a unique link to get the code (user can get that code every 5hrs). I was thinking about making a simple site on which the user would do the task (watch video ad or something similar) and then after that was done the user would get the special generated code... im new to this so does anyone have any suggestions? Where can i get those kind of video ads that would generate revenue etc.? Thanks