Interesting paper in that it claims to have found a common theme of the "Smith and the Devil" story using statistical techniques keyed on particular features of folk tales.

It should also be pointed out that there are many transparently shared story-lines among the IE languages that have previously been discovered just by traditional comparative literature methods.

The most well known of these is the "hero vs the dragon/serpent", which is observed in works as geographically and time separated from each other as Beowulf vs Wyrm in Anglo Saxon legends and Indra vs Vrtra in the Vedas.

Finding vertically transmitted ancient storylines is interesting and even more compelling than the long known vertically transmitted language components like grammar and lexicon.