Go to the [Main Menu] and there highlight the [Play All] selection. Now press the [Right] arrow key on your remote control to highlight two pictures on the pub wall. If you press the [Enter] key now you will see random clips from the documentary.
Hidden Track
The track is "Witch's Promise" and can be found on the [Bonus Tracks] menu. On that menu, select the entry [Play All] to start playback of all bonus tracks. Once they are all through, the hidden track will play automatically.