I think this relies on the particular string being a linear time-invariant channel. There is some limit where the string won't react accordingly (at a certain low or high frequency). What is that later phenomenon called, anyone know?
Hmm the author had to use salt water to get it working. Maybe resistance is the limiting factor rather than dispersion. In which case a higher power modem or some sort of amplifier would get this working over >2m distances.
