Whelp, so far I have:
The Charmers
The Jolly Beggarmen
The Shamrocks Singers
The Studio Group

...and counting, all doing the exact same yTube take on Monto. Any of them sound familiar?

And usually lurking in the wings somewheres:
Passport International Entertainment, LLC.
10520 Magnolia Boulevard
North Hollywood, CA 91601
U.S.A.
Owner of record was: Jeanette Pugliese (daughter of Turner Classics producer Dante J. Pugliese.)