Here are ways to turn looping on or off
Double-click a slideshow button on the DVD menu to open the slideshow editor. Click the Settings button and select the “Loop slideshow” checkbox.
Select a slideshow icon in map view, and then press Command-I to open the Slideshow Info window. Select the “Loop Slideshow” checkbox, and then close the window.
Click a movie or slideshow button on the DVD menu, or a movie, slideshow, or autoplay movie icon in map view, to select it, and then choose Advanced > Loop Movie or Loop Slideshow.
When looping is turned on, a checkmark appears next to the command in the menu. To turn off looping, select it again to remove the checkmark.
To turn looping off for a background movie on a menu, open the Menu Info window. With your pointer over the menu (but with no buttons or text items selected), press Command-I. Move the Loop Duration slider to zero.