There are A LOT of great videos online about how to trim a brisket, but I wanted to focus on those featuring ones done by BBQ joints (brick & mortar, pop-up, etc.). So far I've compiled 16 'How To' videos that should give you a good idea (and guide if you need one) on how to trim brisket like they do at their restaurants.
I will continue to add to this list as I run across new ones or ones I may have missed.
Bradley Robinson - Chuds BBQ and LeRoy and Lewis Barbecue - Austin, Texas
Aaron Franklin - Franklin Barbecue - Austin, Texas
Wayne Mueller - Louie Mueller Barbecue - Taylor, Texas
Blake Stoker - Blake's BBQ - Martin, Tennesse
Johnny White - Jirby BBQ and Goldee's Barbecue - Fort Worth, Texas
Fernando Gonzales - 2Fifty Texas BBQ - Riverdale, Virginia
Mario Ramirez - Alice's Restaurant - Treaty Oak Distilling
Andrew Castelan - Cattleack Barbeque - Dallas, TX
Mike Black - Terry Black's Barbecue - Austin/Dallas
Dayne Weaver - Daynes Craft Barbecue - Fort Worth, Texas
Chef Ara Malekian - Harlem Road Texas BBQ - Richmond, Texas
Brendan Lamb - Smiley's Barbecue - Roanoke, Texas
Mauro Chiefari - Texicana BBQ - Currently Consulting & Putting on Classes - Has worked at Kerlin BBQ, Cooper's BBQ: Austin, LORO Austin, Franklin Barbecue and collabs with Terry Black's Barbecue, Hurtado Barbecue, and Liberty Barbecue.
Joe Yim - Knox Ave Barbecue - Chicago, Illinois
Wilson's BBQ - United Kingdom
Burt Bakman - SLAB Barbecue - Los Angeles, California
Wrapping this up, J.C. Reid from the Houston Chronicle has a great piece on the evolving art of brisket trimming HERE