gluesniffined, likely the reason they're using a proprietary mpeg4 codec is because the open source one typically included with mplayer doesn't use the dedicated video hardware, and on a 200 mhz device, it's needed to have a shot at decoding full size (ie, 720x480) video at any reasonable speed.  Now, 320x240 video may be possible with a ridiculously optimized software decoder (the dreamcast, a 200 mhz SH4, could bearly do it), but I doubt mplayer or its codecs have even an ounce of ARM assembly in them.
				
			
	