thanx Yulor, but it's not about the code.
Lets say I have 640x480 "intro.avi" and play it in media player fullscreen. It plays smoothly and looks fine.
When I do this (and have higher resolution than 640x480)
media_play("intro.avi",null,100)
the quality is much worse and jerks appear, because the cpu can't handle the bitrate. The strange thing is that it obviously can when played in media player (and the bitrate is really low - say 2500kbps).
I remember JCL said something like "files played by media_play are actualy just handed over to DX" (that's the reason why you can't have them in resource) - so I wouldn't expect media player to behave differently from the engine.