This is a kids friendliy offline video player for Android. It queries Android for all video files and displays them in a list. The user can select a video and play it. The app is designed to be used by kids, so it is very simple and easy to use. It doesn't have any settings and anything else that can be "misconfigured" by kids. Use it with app pinning and/or a launcher that doesn't allow to exit the app.
Doesn't have any ads, tracking, subscriptions or anything else.
TL;DR: Reboot your device.
Android keeps an internal media database, which can't be accessed/refreshed and/or modified anymore. Stock android seem to have a setting/workaround on how this database can be refreshed, but this is not available on Amazon devices.
Public Domain.