XBMC for Ouya will not play MP4 files! It behaves like its going to play the audio only of the film but does nothing!
The MP4 files issue goes into a licensing issue that prevented all of the codecs from being compiled into XBMC for ouya (Currently version 12.3 Frodo). Since version 13.x Gothan XBMC has changed its name over to the new platform KODI. If you point your Ouyas Browser over to the New Kodi homepage for downloads and select the Android ARM version. You can download the APK and side-load without the need of rooting your Ouya. The version direct from KODI will upgrade the player to version 14.x helix (At the time of this posting) and you will regain access back to playing videos upon it once again.
As for the hope of having the official XBMC tree for Ouya updated. Chances are pretty slim with the state of affairs Ouya is in right now.