I frequently come across the opinion that behind-the-scenes footage and making ofs somehow ruin the magic of cinema, that somehow peeking behind the curtain and seeing the Wizard spoils the trick. I can't say I ever find that. At all. If a film is good I'll always be swept up, regardless of what I've already seen.
If you fall on the side of finding that it tends to spoil things for you then I would advise avoiding this video of fifteen minutes of behind the scenes b-roll footage from Thor: The Dark World. It's full of a lot of footage that doesn't have the benefit of the waving of a magic wand.
Thor: The Dark World opens in the UK on the 30th of October and in America on the 8th of November. Expect a lot more on the film before then.