I'm VERY familiar with Synthesia. In order to generate those animated videos of falling notes, a corresponding MIDI file for the song has to exist. I would think it'd be better in most situations to build the purported "piano tablature" off of that instead.

While neat from a technical perspective, this seems like a solution in search of a problem.

EDIT: On the other hand, a cursory search did not find any midi/piano sheet music for "Hi Nanna: Samayama" - so maybe only having this "falling note video" is more common for certain music.