Can somebody explain to me ?
 

I can't instal BS free many times . Every time error apears : Crash occurred in filter "VSS Decoder filter" Application may be unstable from now .

VSS filter appears to be an old H264 decoder developped by Mplayer's team. Used to decode H264 and x264 streams, it's no longer under developpement. So, my advice is to uninstall it and install another x264 decoder, such as Core or FFDshow.