The latest nightly build at 1.3.0 is able to play the 10 bit depth h264 encoded video files, but this isn't obvious to the average user. I can imagine the user installing lots of clumsy codec packs to solve the problem. Whatever fixed the issue needs to be merged with the build in the front page as ...
Jean-Baptiste Kempf, the current version is 1.1.12, not 1.2.0. That version has not been reached. 10 bit depth x264 is not supported in the current version. A green screen is shown instead.