After buying a new xbmc / kodi tv box (Chinese clone of mx2) I went through the entire setup, adding the various add-ons just to realize that playing a movie / stream results in audio only playback. No video at all.
Researching online offered a solution by changing from hardware acceleration to software video acceleration. This didn’t help in my case. Finally what actually solved it was unchecking the hardware acceleration for amlogic.
Try all acceleration options to see what solves it for you.