The specifications for the video ad include the following:
Format: The video ad must be in a commonly supported format such as MOV and MP4 files.
Resolution: The recommended resolution is 720p or 1080p
Aspect Ratio: The preferred aspect ratio is 16:9
File Size: The file size should be optimized for online streaming and should not exceed 512 MB.*
Length: The duration of the video ad should be 6, 15 or 30 seconds.*
Subtitles: It is recommended to provide subtitles or closed captions for accessibility purposes (optional).
This can vary from one publisher to another.