Rewarded video is the most player-friendly ad format because it is a value exchange the player initiates. It usually carries the highest eCPMs of the common formats, since viewers are attentive and complete the view.
Its performance depends on the moment. A reward offered when the player cares about continuing — after a meaningful failure, or to finish a goal — gets taken; the same offer before the player has anything worth protecting is ignored. Poorly placed rewards can also become an escape from friction the game itself created, which teaches players to resent the loop.