It's whitelisted based on the embedding domain. https://support.google.com/youtube/answer/132596 https://support.google.com/youtube/answer/132596 >Ads appear

It's whitelisted based on the embedding domain. https://support.google.com/youtube/answer/132596 https://support.google.com/youtube/answer/132596 >Ads appear on brand safe sites: YouTube works diligently so that our advertisers' brands appear on sites that reflect our respective core values. Our systems closely evaluate websites and their content against various factors when finding out whether to turn on In-stream ads on YouTube embeds. These factors include a strict set of guidelines on content like adult imagery, violence, inappropriate and hateful language, and sites that promote infringement.