Hello Tommy,
The Tiny Arcade is actually modeled around the hardware of the TinyScreen+, so you should be able to upload the program from the TinyScreen+ Video Player tutorial to your Tiny Arcade just fine. This tutorial includes a program that lets the Tiny Arcade simply play the videos on the microSD card when powered on, without a menu.
If you want to get your Tiny Arcade back to having the menu for games and videos, follow this tutorial:
https://tinycircuits.com/blogs/learn/171319495-tiny-arcade-menu-update Then you would be able to play the games with the menu choice, as well as have an option to play videos alongside the games on the SD card.
The length/file size of videos loaded onto the SD card are limited by the size of the microSD card you have.
You don't need to use boot mode each time you upload a program, only if the board seems unresponsive to programs or the port is not showing up when you go to program it.
Thanks for the renewed interest! We hope the addition to your daughter's dollhouse looks great!
-Laveréna