Using the SDL video output, the video window does not respond to the noborder command line switch. MPlayer version Sherpya-SVN-r34401-4.6.2.
Steps to reproduce:
1. Run mplayer -vo sdl -noborder file.avi
A video window without Windows border and decorations.
A video window with Windows border and decorations. Compare with -vo direct3d -noborder to see intended output.