Video ads are now supported in display campaigns:

• The AdGroups service now supports ad groups with the CPM_VIDEO_AD_GROUP type.

  Restriction. The Gather audience by completion rate setting is currently not supported in the API.

• The Ads service now supports ads with the CPM_VIDEO_AD type.
• The Creatives service now supports creatives with the CPM_VIDEO_CREATIVE type.

You can find more detailed information about managing display campaigns in the API in the documentation.