It depends, I guess, on the Flash player that you are using. Many "out-of-the-box" solutions do not allow for hiding the scrub bar. If you are building the player yourself, it is absolutely possible, as I have done it in the past.
If you are using the FLVPlayback component in Flash, you can go to the component inspector and choose "SkinOverPlayFullscreen" from the skins that will allow the player controls to display only the Play button and the fullscreen button. There are other skins that do not contain the scrubber bar, so you could choose one of them, or even create your own.
I'm pretty sure you could get more detailed advice if this subject were moved to the Flash forums. If a mod happens to see this, it might be more helpful to Eric to move this topic there.