Found the reason on Kodi FAQ
http://kodi.wiki/view/Android_FAQ#No_vid...ying_files
No video/black screen, only sound, when playing files
Link
The three most common causes of only having sound, but no video, when playing a video file are:
The hardware in the box is AMLogic-based and another video/media app is running in the background. Quit the other media apps or restart the device and XBMC should display video again.
The hardware in the box is AMLogic-based and the firmware (Android installation) didn't set certain permissions correctly and isn't rooted. The easiest way to fix this would be to either root the device, so that XBMC can set the file permissions, or update to a better firmware that sets the correct permissions.
XBMC thinks the video can be decoded using video hardware/acceleration, but the encoding just isn't right. Using software decoding might be a work-around: Settings -> Videos -> Acceleration
