Companion Ads are text, display ads, rich media, or skins that wrap around the video experience, and can run alongside either or both the video or ad content. The primary purpose of the Companion Ad product is to offer sustained visibility of the sponsor throughout the video content experience.” See http://www.iab.net/wiki/index.php/Companion_Ad
Kaltura’s platform makes it easy to add Companion Ads in either HTML or Flash. After you’ve configured your player (see How to design and configure a player in a playlist?), edit the player and navigate to the Advertising tab. Scroll down a bit to the “Player Configuration” section.
Choose whether to configure HTML or Flash-based Companion Ads.