New with Stream GA (6/20/17) a video can have any number of owners who can be either individual users, AD Security groups, or even an Office 365 Group can be an owner. If you make an O365 Group an owner only the members of the group who can contribute to the group will be able to edit the video.
For more information on permissions/privacy/ownership see this Stream help article:
https://stream.microsoft.com/en-us/documentation/stream-portal-permissions/
