The Teensy LC looks great, and I'd love to get my hands on one!

If I was lucky enough to receive one I would use it to simplify my project.

As it stands I plan to use an Arduino Nano to manage my buttons. I order to do this I will require my Python scripting to monitor the arduino's output over serial. This script would then need to pass commands to my video playing script.

Using the Teensy's HID capabilties, however I would be able to send standard key presses and just have my video playing script respond to what it considers a normal keyboard! :-)