Depending on which editor / effects SW you're using, you may find this as an existing effect.
If you have to do it yourself, first desaturate -- convert to greyscale.
If you then simply increase the contrast until only pure black and white remain, you may be disappointed in the result, because video generally has a low-ish APL (average picture level), so most of the image will turn black as it's stretched to the two extremes.
To counteract this, first (or simultaneously) increase the gamma of the image, to raise the APL into a centered range. Only then max out the contrast.
Playing with your actual images is the only way to know where the knobs should be turned, but it's important to know what knobs there are and what they do.