While that's true, the Scrugg's peg was really quite an invention for those of us that appreciate Bluegrass Music as only Lester Flatt and Eral Scruggs could play. The device was later perfected by Bill Keith but were used for the same thing. They were also called "D-Tuners" enabling the player to oscillate quickly between G and D. Although this player is using a Keith peg, it works the same as the earlier Scruggs:
The Scruggs pegs (always fitted in pairs) were earlier than the Keith devices, and more basic (ie possible for the DIYer to make himself). See the link below for description and a really clear set of photos.