OK, looking at the output it looks like this is a bug. I personally don't use MPlayer as it is notoriously buggy.
What do you use/suggest instead - vlc?
Oh, ok. I usually don't use the SDL output as I have no requirement for it.
For me, -vo sdl is the only output that gives decent performance. The Radeon HD5450 doesn't support xv on openbsd, and x11 plays at about 5 frames per second. sdl is smooth but suffers from some screen tearing when there is lots of movement on the screen.
