Link to an explanation of the Mandelbrot Set: https://en.wikipedia.org/wiki/Mandelbrot_set
A Mandelbrot Zoom simply zooms into a tiny piece of the Mandelbrot Set. Theoretically, one could zoom into any part of the Mandelbrot and continue to find self-similar-but-not-exact fractal-math flora, infinitely. With a powerful enough computer and a few months time, one can create the YouTube Mandelbrot Zoom as shown here in HD: