the only video showing that piece is "foggy Mountain chimes" where he uses it, much the same as scruggs tuners are used on banjos.

Looks like a standard Hipshot "Doubleshot" to me. Popular for many players these days.
 

Howard of course nailed it - it's the DoubleShot from the Hipshot company. A lot of players refer to the device simply as the "Hipshot" which is not exactly correct - the DoubleShot is one of dozens of products available from Hipshot. 

I can see where Jerry House might refer to it as being something like a Scruggs tuner, but that was unique to the particular video he mentioned which I posted below. It's not typically how it's used. The vast majority of dobro players set up the DoubleShot to be able to switch back and forth between G (lever down) and D (lever up and back). If you like to use both tunings, it's like having two guitars for the price of one (except the DoubleShot keeps going up in price!).
 

so basically just an expensive way to change tunings on the fly, and not for special effects. got it!

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Originally posted by majorjer

so basically just an expensive way to change tunings on the fly, and not for special effects. got it!

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It's really a guitar engineering marvel. Check one out.

Here is a  good explanation by Andy Hall from around five years ago.

Pricewise, the double shots may be more like having 2 guitars for the price of 2....but without 2 Fishman pickups to buy, 2 cases to haul to a gig, 2 instrument stands on a small stage, double tuning/string changing; nor is there the "which tuning for which instrument" conundrum. And....no bandmates standing around waiting for you to switch, no headaches trying to arrange the song order to flow musically while minimizing changeovers. And so forth....

quote:

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Originally posted by majorjer

so basically just an expensive way to change tunings on the fly, and not for special effects. got it!

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If you've ever retuned from G tuning to D tuning you'll know how it's a project that takes a few minutes. There is a considerable difference in overall tension so as you retune each string the others go out of tune. Getting all the way there means going through each string two or three times. Same with going back to G from D tuning. In the Kathy Kallick Band we added a few tunes where I used D tuning and the retuning was a pain and time consuming. The last straw was where I had to go from G to D and back twice in a set! Once the tailpiece is dialed in you can go back and forth accurately with the flip of the lever. Being a banjo player it wasn't long before I realized I could also use it like Scruggs tuners and I came up with Foggy Mountain Chimes on the dobro, complete with the chimes in D tuning just like Earl did it. 

Greg, that vid “Foggy Mtn Chimes” is great. And from now on I’m calling my Hipshot Double Shot the “Greg Booth Tail Piece”, or as it will eventually be called, the GBTP.