Playing a locally stored mp4 files while MagicMirror is active

[Sputnik]

I tried various ways to get a short mp4 file playing while the mirror is up.
I added omxplayer commands within the config.js file and stored the mp4 file in the same folder. That didnt work.
Could I startup an python file within the config.js and the python file would then do some GPI pin (sensor) controls an start the file ?
What would be your suggestions ?