Actually, the "brake" isn't something set in software. It is a Jumper on the victor itself. You use a tiny jumper to connect either pins A and B or B and C to create either "Brake" or "Coast" mode. Brake mode simply slows the motors much more, and makes it harder to backdrive. A common use could be on a mechanical arm, to prevent it from lowering too fast while power is not being applied. Coast mode is usually used in two or more motor drive systems, to prevent braking at different rates, and ultimately making magic smoke.
Learn from experience and make sure you set all ESC's in the same mode, if you set one side to brake and one side to coast, you will have major drift. It's kind of upsetting trying to figure out what is causing this dift at 2:00am in the mech room.. *sigh*
-Kris Erickson