videoplayer Unity 5.6.1: videos only playing on windows standalone when building on a Windows pc

I am working on a MAC (macOS Sierra) with the latest Unity version (Unity 5.6.1). In my project there are some videos playing with the Unity videoplayer, using transcoded videoclips. Building for iOS works fine. Building for macOS works fine. When I generate a standalone build for Windows, the videos do not play. When I open the Unity project on a Windows pc (WIN8) and build for Windows, the videos play. I also tested the cloud build feature: when uploading the project from my mac the standalone windows version does not play the videos.