I don't know how to get the scenes. Is it just based on luck? And is there only one scene? (I also see these nights in order: night 1, night 10, night 2, night 5, night 8. is this a bug?)
If you talking about the new build 0.8, its a test build, so there is not much in it because its a early alpha test.
If you talking about the old build 0.75, you an check the unlockboard for how to unlock them, but they made like a riddle.
Some of them are unlocked by finding the secret tapes thats placed around in the game.
The demo might only have the gameplay, and no scenes.
If you experienceing a issue with the nights being jumpy, then it might be a broken save file or folder, so you might have to make a fresh one. Might also check if the extraction of the files are fully exctacted, since some experience the folder or its files gets blocked by anti-virus, so you might have to whitelist the folder and its content. If you dont get blocked by anti-virus, then there should be no problems.