There is really no point in playing HD video on X8, because on 360p screen (480x360), you obviously can't watch 720p (1024x720) or 1080p (1920x1080) in their real resolutions
so for an example:
if you have one video in 360p, 720p and 1080p, and let's say that you want to watch this video on a device that supports 1080p but it has 360p screen (like X8),
you will end up with that, that you can't distinguish 360p from 1080p video
so my advice would be for you to resize it to 360p, put FPS on 20-23, maintain the sound quality, and that is as much as you can get on X8 regarding playing videos