What he means is that after you have just flogged your car around the track your brakes if not let cool down can have the pads bind to the disc.
Thats why F1 teams shove a leaf blower up the brake cooling ducts when they stop for a extended time in the pits.
V8SC teams are doing the same i noticed the other day.
Before leaf blowers we used to rock the car back and forward for a few minutes to let brakes cool.
The block is if you are not on level ground, its a chock to stop the car moving and not use your hand brake if you have one.