Some dude with an acoustic guitar one day decided he needed to know what Metallica songs look like from the inside, so he put a camera in there. Simple! Though I'm sure once he took it out and watched the footage he was a little surprised at the results. It makes sense though, given the strings are moving way faster than the camera can capture, giving that wavy look.
Nice! If anyone can help me credit the original poster, I'd appreciate it as well.
