What you pay for
You only pay for the video views you acquire from your campaign. You can choose your bid unit: per pre-roll video view (defined as 2s at 50% in view), per 3s/100% pre-roll video view, or per 6s pre-roll video view. Impressions that don't result in a view are free.
You can also choose between maximum and automatic bid, and can set a total budget and daily budget for your campaign so you have complete control over its spend.
The cost you pay per engagement depends on your set budget and bid, as well as your targeting. You'll receive real-time bid guidance during the setup process.