Back then, i was managed to make my N900 plays 800x600 mp4 files converted with Format Factory.
However, last month, i reinstalled window but forget to back-up the custom profile.
Now i can't remember how did i do it, tried some Mobile Device Compatible MP4 with 800x600 res but it's still not work (it works with smaller resolutions though). The error : Cannot play media files. Media format not supported always popped up. I have to reset every time i try to open it.

Can someone help me with the setting or upload the profile for me?

Thanks in advance

Sorry for my bad English xD

And after resetting, is that work? The N900 does not natively recognize the H.264 video codec which tend to be the default standard for the mp4 files, you must configure your software with the MPEG-4 video codec.
And install (on your N900) the extra decoder support called décodeur A/V supplémentaires from http://maemo.org/downloads/product/M...oders-support/

http://wiki.maemo.org/N900_Video_Encoding

use handbrake, just remember to disable weighted-p-frames, set output to 800x480.