Fetches the latest metadata for a video generation job identified by video_id.

Behaviour and response shape align with the
OpenAI Retrieve video API
(same Video object as create/list flows): status, progress, timestamps, model, prompt, size, error payload, etc.

Response fields vary by provider. Some backends omit fields that OpenAI always sends; progress,
seconds, size, prompt, usage, and timestamps may be null. id may be a long
provider-encoded string (e.g. video_… with embedded routing metadata). Job failures may surface under
status: failed with error.code as a number (e.g. gRPC-style) instead of a string.