AdWords for video is the offer developed by Google for displaying video ads on YouTube and on Google Display Network.
The video campaigns are managed from AdWords platform as for other ad formats. The advertiser pay only when the visitor choose to watch the video, it is called "true view" by Google. What is a true view vary according to the type of video ad placement.
Adwords for video offers 3 networks for delivering video ads and 4 types of ad placements or formats.
4 video ad formats:
Video used in campaigns must be uploaded on an YouTube account associated with the Adwords account.
Implementing a video campaign on AdWords for video: