Include this feature in D2X-XL: If Descent 1 Movies are present in the movies folder, allow for the disabling of the briefing screens (except for the planet destination screen and the robot description screens), so that when you play Descent 1, you will see the briefing movies, then the planet destination screen, followed by the robot description screens, and then finally play the actual game much like Descent 2.
The movies should replace the corresponding static briefing screens. If this is not the case, that would be a bug.