XBMC
XBMC is perhaps the only application most HTPC users use to reproduce media files (video, audio and pictures) and i have to admit that I’m very fond of it myself.
Rikomagic is using the 12.4 FLUMP version of XBMC which by default has a nice home theater setup as background.
Unlike NAS servers you don't have the ability to change the resolution and audio output from within XBMC but you can change its looks/layout.
You can also check various information screens about the hardware specifications of the player.
Although we were unable to playback our Blu-Ray RIP of Avatar (we used a 32GB microSD card for our tests and that file is over 40GB) we did watch several movies without a single issue.