Source: http://lifehacker.com/5568839/rockplayerbase-plays-divx-avi-and-other-videos-you-want-on-android
Android: By default, Android phones can only handle a small number of video types, and leaves your ripped and downloaded files in the dust. RockPlayerBase, on the other hand, nimbly plays DivX, AVI, XviD, MKV, and other file types.
The bad news is that RockPlayerBase isn't available in the Android Market just yet, but is widely available in beta form if you poke around on Google—the via link below, Android Community, and others have posted media hosting links. It's a very minimal application—it launches with a file browser, then jumps into a player when you've picked your file, with simple play controls and timeline scrubbing. You'll see the frames-per-second count in the upper-right corner, but you can kill it by clicking the DivX button once or twice.
RockPlayerBase is, at the moment, a free download for Android phones running 2.1 and above only. Be sure to grab it before your next flight.