Or, if you are asking how to author a DVD that will simply play over and over all by itself this can be done as well.

I do not know what authoring software you are using so I have no clue what command to use, but a DVD will return to its originating menu, by default, whenever it finishes. You can edit this using your menuing software to make it go back to the beginning of the video if you wish.

Also, I believe you could author your DVD to contain only the video (with no menus) and I think this will make the video automatically repeat.