It looks like a viscoelastic tape from 3M (~100$ for 1"x60yd roll) It basically converts the vibration into heat, but I'm having trouble with the size of those patches on that bike, because damping performance of such a tape is
also dependent on the geometry, mass, stiffness and the temperature (!) of the object to which it is applied...
also dependent on the geometry, mass, stiffness and the temperature (!) of the object to which it is applied...