in my system (2.6.37.2-desktop-1.mga #1 SMP Sat Feb 26 01:40:03 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux), I can not play videos mp4a

We would need to know your distribution, what media player you are using, and whether you have any mp4 codecs packages installed.

LSB Version: core-2.0-amd64:core-2.0-noarch:core-3.0-amd64:core-3.0-noarch:core-3.1-amd64:core-3.1-noarch:core-3.2-amd64:core-3.2-noarch:core-4.0-amd64:core-4.0-noarch:cxx-3.1-amd64:cxx-3.1-noarch:cxx-3.2-amd64:cxx-3.2-noarch:graphics-3.1-amd64:graphics-3.1-noarch:graphics-3.2-amd64:graphics-3.2-noarch:lsb-2.0-amd64:lsb-2.0-noarch:lsb-3.0-amd64:lsb-3.0-noarch:lsb-3.1-amd64:lsb-3.1-noarch:lsb-3.2-amd64:lsb-3.2-noarch:lsb-4.0-amd64:lsb-4.0-noarch:lsb-4.1-amd64:lsb-4.1-noarch
Distributor ID: Mageia
Description: Mageia 1
Release: 1
Codename: frites


smplayer, vlc, dragon

installed mp4:
lib64mp4v2-devel:Core Release
libmp4v2-utils:Core Release
lib64mp4v2_1:Core Release

Can you verify that these mp4a files are playable elsewhere? Given that such a range of players (vlc and mplayer mainly) cannot play it, it could be corrupted.

I tried a few mp4 files that I played in kubuntu and Mandriva 2011 maverick, but do not want to move magei.