Lead cyclists take turns riding at the front of the pack (the peloton, from which the company took its name), blocking the apparent wind and allowing teammates to ride in their slipstream. The protected riders use less energy to maintain the same pace.

Peloton is the same idea as tailgating (driving behind a truck on highway in order to save fuel), front cyclists/runners use extra energy to "break" the air so that those behind them can save some strength.

Tailgating is just what jerks do because they are inconsiderate and unsafe.

I believe the word you were looking for is "drafting".

If you look on youtube for this event, you'll see there was a vehicle driving in front of the pack that was aiming a laser at the feet of the runners. It appears to make it easier to follow a pace very accurately by making sure your feet are following the laser.