Says Matt Whitcomb about the video:
The session is repeated once per week for many of our athletes. We alternate classic and freestyle. The protocol is 3 sets of 5-8 reps. Each rep is 8-10 seconds in duration. The first set is starts, then transitions, then dropins (or overspeeds). To allow the energy systems to properly recharge, allow for 2-3 minutes of easy skiing between each rep, and 10 minutes of easy skiing between each set. The warmup protocol is 30 minutes of easy skiing plus synamic stretching. Cooldown as needed, but usually 15 minutes to keep the workout duration under 2 hours.
These are all out sprints, exceptionally short in duration, with a exceptionally long recovery between repetitions.
One interesting aspect is the speed intervals through a transition. You'll see in the video that the skiers begin with a doublepole, then start up a steep hill and transition to diagonal stride. I'd never thought of doing transition as part of an 8-10 second sprint before!
The "overspeeds" are done on a slight downhill so the skiing is faster than normal. In a "dropin", the skier gains speed on a downhill, then starts the interval on the following flat.
This is the US Ski Team version of a speed session. So what does the aspiring young racer or master skier do? You should probably start out with just 5 speed repetitions and work your way up. Don't rush the drills - make sure you have sufficient recovery between reps.