IIRC kmplayer also can zoom video. It´s a bit funny thought, you will lose information if you zoom video, but users who do not understand what is happening will be happy because of "full screen".

Still this is utterly user end failure :| You have to at least have some knowledge about aspect ration and resolution before you can say anything about full-screen and how stuff works. So to OP please learn at least basics of these things before posting this kind of posts.

.edit
Of course there is also option TO force movie to resolution of N900 but then again happens same thing what currently some widescreen users are get used to. On widescreen television when forced aspect ration is used people tend to be too slender or fat and that at least makes my head explode :| "look it´s full screen and Angelie Jolies boobs are even bigger...whoppidoo". BANG - headshot...