By the way, I have a Larrivee parlor guitar that I have strung in Nashville tuning. In my opinion, this tuning is ideal for the 3/4 sized guitar. Full-sized "cannon" guitars like the one in the YouTube video aren't really designed for the reduced tension on the neck.

Here's another YouTube clip, where the guy is using a 3/4 sized guitar: TB-505 • Nashville Tuning on Guitar (Lesson)