My first thought was what a waste. Should be a mouth around that cock. Just the way I think.

But as I watched it that thought changed to 'ouch'! Looked painful.... to me anyway.

As with anything be careful:

Electro stimulation can cause tissue damage or even death if misused. The most common problems arising from electro stimulation tend to be burns from lack of lubrication or bad contact between the electrode and the skin's surface. Even at relatively low current and voltage, there is the risk for electrocution resulting in heart failure, and is higher for those who use an artificial pacemaker or similar device or who have heart conditions. Because of this, it is not advised to place the electrical contacts above waist level.[1] Among people who engage in electro stimulation, newcomers are encouraged to research the hazards, limitations, and techniques of this practice and the devices used.
http://en.wikipedia.org/wiki/Erotic_electrostimulation