Playing video on Nintendo DS

I tried to convert a 60 minutes video ([TVBT]Densha Otoko_Ep_01_ChineseSubbed.avi) using dmvtools for watch on Nintendo DS. The result was far from stella. The file size is about 878Mb! Comparaing with the original 231Mb rmvb file, such huge difference is just unacceptable. Guess I should forget about using NDS as a serious media play.