***Disclaimer: I've never used this module...
I think the module isn't loaded. Check if /usr/local/freeswitch/mod/mod_mp4* is in installed. Also make sure it's loaded in /usr/local/freeswitch/conf/autoload_configs/modules.conf.xml.
If so, then check the trace in /usr/local/freeswitch/log/ to see why it didn't load.
If it's not installed, then install it:
1. Edit modules.conf and add applications/mod_mp4 to it.
2. make
3. make install
4. Edit conf/autoload_configs/modules.conf.xml and add this line:
<load module="mod_mp4"/>