If so how do you change it?
I notice that some mpegs just roll one to the next and leave the window consistent.
But some seem to control and make changes to the sizing, which you dont want if you have multiple stuff open. It means resizing the window.
CAn I avoid it?
Are you using Windows Media Player? You want to right-click on your first video, choose “Video” from that context menu, and untick “Fit Player to Video” but leave “Fit video to Player on resize” ticked on the second context menu. The setting should persist to the next vid you open. That seems to work for me with all movies, both MP4s and AVIs.