They go into how the Leafs defend at the 20:50 mark. The vocabulary might be new to someone with a traditional coaching background because the strategy borrows heavily from other sports, especially basketball, and teams like the Warriors and Bucks.* They aggressively attack the ball to get teams off their primary play, and trust their defense to scramble into position to defend subsequent actions.
The trade-off for this pressure is that if the defense blows a rotation, you're giving up a wide open shot that you wouldn't have surrendered had your guys just stayed home. The same is true in hockey, if you can move the puck ahead of the Leafs defensive rotations, someone is getting a stupendous chance.
*If you want a basketball history lesson, the modern application of this defensive strategy descends from Tom Thibodeau's trap and recover pick-n-roll coverage with the Celtics, which was then adopted by the LeBron-era Heat. They turned their defensive pace up to 11 by playing the undersized Chris Bosh over a plodding, traditional center which let them switch their nearest guys to every action.