MovieTexture will not play in Build - Black Screen

I’m trying to create a build of my project, and after struggling to get the videos even loaded into the project, it finally works in Unity. But now, when I create a build (Mac or PC), the MovieTexture just shows up as a black screen. I’ve tried both RawImage and OnGUI implementations, both produce the same result.

Try this to make shure your movieTexture is ready to play.

while (!movieTexture.isReadyToPlay)
     yield;