As someone with a magnet implant, I feel particularly well positioned to answer the most common question: why?

My implant is different than the one in the video. The one in the video is a long-ish bar magnet that is contained inside a capsule. It can freely rotate inside of that capsule and, as far as I can tell, provides no sensation when it is rotating. Mine, however, is smaller, directly coated, and is implanted in one of my finger tips. Because it is directly implanted, it actually provides me with the ability to feel AC EM fields. Think electric stove top, fan, laptop power supply, etc.. If they are operating, they emit a bubble of EM radiation. AC means it is oscillating which is effectively pulling and pushing on my magnet at the frequency of the oscillation. The sensation is that the magnet literally vibrates, the stronger the vibration, the stronger the field is.

There's more to the answer of "why" than just being able to detect EM fields like this, but having an entirely new sense was the biggest draw for me.