Back in 2007, Google introduced video ads (Click-to-Play Video) in AdWords API, that has significantly improved with more flexible support for handling various ad types, "TemplateAd," which allow an easy way to introduce new ad types, defined through template ad formats, without having to add new ad types. In turn, this makes it possible to release new ad features and updates much faster without waiting for next version of API," writes Google.
"Before a video ad can be created, campaign must be set to show ads on content network. Video itself must be uploaded to your account via web interface (instructions). Once uploaded, it's assigned a media ID, one of the elements required to create a video ad, which can be retrieved through MediaService's get() method. Now you've everything you need to create a video ad via AdGroupAdService using Click-to-Play Video template ad format. Client libraries have examples for retrieving a media ID and creating video ads in various languages."
More Info: Example in Python