AdSense for video allows publishers with video content (e.g., video hosting websites) to generate revenue using ad placements from Google's extensive advertising network. The publisher is able to decide what type of ads are shown, with their video inventory. Formats available include linear video ads (pre-roll or post-roll), overlay ads that display AdSense text and display ads over the video content, and the TrueView format.
Publishers can also display companion ads - display ads that run alongside video content outside the player. AdSense for video is for publishers running video content within a player and not for YouTube publishers.
Link unitsLink units are closely targeted to the interests of your users. Because users directly interact with the ad unit, they may be more interested in the ads they eventually see.
AdSense publishers are paid for clicks on the ads that are linked from link unit topics, not for clicks on the initial topics themselves. The ads on the linked page are pay-per-click Google ads similar to those shown in regular AdSense ad units. Link Units