This is on Cube U30GT-H using HDMI in a 4:3, 19 inch monitor Hanns G.

Using Mx Player while playing video go to ->Display then ->Aspect ratio,

the video will stop automatically and a pop up window will show different

resolutions, for a 4:3 monitor chose 2:39:1, note that the image on the

tablet will change as well, press back button and enjoy the proper 16:9 display

on the 4:3 monitor.

By the way the MX Player version used to do is 1.7.10,

and the rom used is kasty-cube_u30gt_h-41-111-rooted2.

Hope this helps.