I recently bought a new chinese 7" Tablet running with OS 4.0.3 Ice Cream Sandwich. It came with a sample movie in MP4 format and it plays with the OEM video player installed. The problem was that when I tried to add new mp4 movies on the Micro SD Card, the new mp4 movies were not detected. I was able to solve this problem by installing from Google Play the MIX PLAYER software and finally, I was able to play the new mp4 movies I saved on the Micro SD Card.