McGill Ab Brace - Core Stability

The most common mistake is bracing the transverse abdominis or rectus abdominis (6-pack muscles). Proper ab brace focuses instead on the obliques.
Find your obliques and press the fingers about one inch into this area. Activate these muscles and feel the fingers being pushed out laterally.
Activating the obliques will engage the other muscles of the "abdominal hoop" (core).
The ab brace is a basic building block for all core exercises. Movements such as pushing, pulling, or lifting heavy objects require core stability.

[@peek-ka-boom6017]

I should avoid any movement with what you mentioned at 1:38, right?

[@ryanhollien3570]

Yes. A proper brace will prevent unwanted buckling of the vertebrae during heavy lifting