AVideo: Unauthenticated IDOR in playlistsVideos.json.php Exposes Private Playlist Contents

WWBN AVideo is an open source video platform. In versions up to and including 26.0, the `objects/playlistsVideos.json.php` endpoint returns the full video contents of any playlist by ID without any authentication or authorization check. Private playlists (including `watch_later` and `favorite` types) are correctly hidden from listing endpoints via `playlistsFromUser.json.php`, but their contents are directly accessible through this endpoint by providing the sequential integer `playlists_id` parameter. Commit bb716fbece656c9fe39784f11e4e822b5867f1ca has a patch for the issue.