How ads are chosen
Monetized YouTube videos may display ads served via the AdSense auction as well as ads sold on a reservation basis via DoubleClick (DCLK) and other YouTube-sold sources.
The Adsense ads displayed on your video are determined automatically by our system based on a number of contextual factors relating to your video. These factors include but are not limited to your video metadata and how you categorize your video.
We aren't able to control all of the ads that appear with your videos manually. Similarly, we can't guarantee that specific ads will be displayed with your videos. We regularly monitor and update our content-targeting algorithms in order to deliver the most relevant ads to your video pages.
Please Note: At this time we are not serving ads on videos that are enabled as 3D videos.