I wrote the app in Python for the Raspberry Pi. For video playback I am using the (now deprecated) omx player.

I tried using VLC instead for video playback (I think the more accepted way to play video from Python now) but when VLC completes showing a video there is a visible flash that I cannot figure out how to get rid of.

I should point out though that it doesn't "stream" — you'll have to find some other solution for that. The Pi is a dedicated "player" hooked to a dedicated TV that is always on, always showing what the Pi has to offer up.