In addition, importing an MP4 video does not work in windows desktop version. An exception is raised telling that a null texture was returned. The video is correctly encoded in h.264.
My game is going to be available in various platforms. This is a potential problem for me as I can see the video features are very buggy right now. Anyway, I just use videos to present the studio and the publisher, so I think I will be ending using static images instead.