If it's a static image or a video that you also don't want to repeat, then just make sure that the End Action for the menu is set to Hold (which it is by default, anyhow). The DVD player will go through the menu once and then simply display either the static image or the last frame of the video, as the case may be.
If you want a video background that loops but with audio that doesn't, then you can either insert an introduction media that includes your audio or create one long video for your menu that starts off with the audio but extends past the end of that audio. Then set the loop point for the menu to someplace after the instructional voice-over finishes. You'll want to create the video background in such a way that the the loop point won't be too jarring.