Given scene/plot descriptions from movies or TV shows, and given a specific question about the scene, summarize the question into a title

Snape had already told Voldemort about the prophecy, or at least half of it, so what is the point of seeking that prophecy once again? It doesn't seem to have anything that would have been helpful for him to defeat Harry.
Why did Voldemort want the prophecy in Order of the Phoenix?

In Dark City, everybody seems to have memories of Shell Beach planted by Strangers which doesn't even exist. It also gave the main character a reason for searching it. But why did the Strangers imprint the memory of Shell Beach when they were not even supposed to remember where it exists? Why did the Strangers make this memory loophole?
Why did the Strangers make up Shell Beach in human's heads when they were not even supposed to go there?

In episode 4 of season 1 we see Locke taking its first look at "the monster" (~30:00), while hunting boars on his own. He seems to be looking straight at something, not just randomly towards the direction of the noises. But then (~38:53), when asked by Walt's father, he says he didn't see it.  Why does he lie?

Why didn't Locke say he saw the monster?

