Ads, how do they work?

PLAY AN AD IN THE BEGINNING OF VIDEO; PLAY AN AD IN THE BEGINNING OF VIDEO AND ANOTHER AD AT THE ONE MINUTE MARK; PLAY AN AD AT THE BEGINNING OF THE VIDEO, AN AD AT THE ONE MINUTE MARK, AND THEN AN AD AT THE END OF VIDEO; PLAY A 15 SECOND NON-SKIPPABLE AD AT THE BEGINNING OF VIDEO, TWO 30 SECOND NON-SKIPPABLE ADS AT THE ONE MINUTE MARK, AND THROW IN A 3 MINUTE AD AT THE END OF THE VIDEO THAT’S OPTIONAL TO SKIP