I think you're a little missinterpreting "fullscreen". OMP and vanilla Media Player all have fullscreen option - with respect for aspect ratio, which is why you have black stripers. OMP also have optiom to zoom, which get rid of black stripes, at the cost of leftmost and rightmost part of video.

What you want is, literally, "streetch to screen" (i know you used this term too, you just seem to use it and "fullscreen" for the same thing), which of course, disortes aspect ratio, horribly.

Why you would want something like that is beyond me, but, of course, I respect your right to find strange things useful. Sadly, I have no idea, except for re-encoding your files to contain only one audio track, for use with kmplayer.

BTW, as you want just to, literally, get rid of bonus audio tracks, you can do it in lossless way (good FOSS video editing tools have this option, if youmre not touching video stream, like in this case).

/Estel