okay new complaint for ya (sorry) how come some play on VLC player but some play on quick time (sadly to say my quick time sucks and can't work)

some programs register file types to run in their program, all you have to do is when you install vlc, choose what file types you want to register (play) with it automatically when you double click the videos icon

or in explorer's tools>options>file types, choose what programs to register what files

or run vlc and then click file>quick open file and run the video from there

I mainly use tcpmp for windows (the core pocket media player) because it uses even less cpu than vlc does