Lists the videos in your library that had no access in the date range: no play and no view. A video whose player loaded without anyone pressing play counts as accessed and is not listed.

• Videos created after start_date are excluded, since they did not exist for the whole range.
• Results are ordered by creation date (oldest first) and are always paginated, up to 500 per page. Use pagination.total_unwatched and pagination.has_more to walk the pages.
• If some day of the range could not be read, coverage.partial_coverage is true and the day is listed in coverage.missing_days. A video accessed only on those days may still appear in data.