An official Google statement said:
Video processing runs in a "customer-owned private instance" and is not automatically accessed by Google employees.
All processing requires user authorization.
System-generated summaries and test results are intended for user viewing and are not shared with advertising systems or third parties.
Google emphasizes that it adheres to the Privacy Shield Principles; however, it is a matter of personal judgment as to whether or not users trust it.
Videos are not used for Gemini model training unless explicitly authorized by the user.