Disagree about the video fixing it, they can just ignore your footage. I make them sign a written condition report WITH photos the minute I get the keys. Every scratch on the furniture gets written down and we both keep a copy. That paper is your only real leverage later.

That 'suspense movie' feeling @benn32 mentioned is so real. When my last place had foundation cracks, I made sure to get a second opinion from a structural engineer. He explained every noise and shift in plain terms, which calmed me down. He even showed me photos of similar houses and how they settle over time, so now I know which sounds are normal.