Erasable pen? With friction?

Ok, so slightly random post... I was playing with my erasable pen, when Teresa pointed out to me that the pen was called a "Frixion pen". Hmm, I thought. Physics blog? So today, I went and googled the pen.
According to Amazon, the pen features "thermo-sensitive gel ink that disappears with simple erasing friction". You rub the back of the pen against the paper, and the ink disappears. Supposedly, the heat created by the friction of the pen rubbing against the paper makes the ink change to clear. It works... mostly.

This means that the kinetic energy of the pen's movement is being converted to heat, and so kinetic energy is being lost. This also means that the friction constant must be pretty high to subtract a significant amount of heat. Sure enough, the back of the pen feels sort of sticky and rubbery, and after rubbing it for a while it gets a little warm.
Video is strangely fuzzy, and has odd hissing and high pitched noises in the background...