That extra windows bug still needs fixing. As I said above:
You know how you can use the audio menu to select what track you want and only one plays at a time (and the same for subtitles)? Well I believe that there should only be one video track playing at a time (selectable from the video menu, just like you have a menu select for subs and audio), that will play in the main player window and no new windows will spawn, and this would be the default.
However there should be an option in the preferences dialog that would enable playing of all video streams simultaneously if one wanted that (and further options to let those be either in separate windows, or all playing in the same window arranged in a tiled pattern provided that the multiple streams have the same frame rate and image size). I would like to see such improvement to the software in one of the next released versions.