I watched the video, and the magnet thing seems pointless. Even if there is a point, why not avoid the hassle and risk of implantation and just carry the magnet around in your pocket?
That would be practical, but I guess the point isn't to be practical. The point is to get attention and to be "cutting-edge". I see this as yet another result of nerd and hipster subcultures colliding, producing something even more unhealthy than either in the process.
You wouldn't feel anything from a magnet in your pocket. The point of the implant is that it is small and touching a lot of your nerves, so the field can be felt.
http://www.theverge.com/2012/8/8/3177438/cyborg-america-biohackers-grinders-body-hackers