Each side have their own objective of improvement. The baselines work on their passing shots, and the volleyers on their volleys and positioning as a doubles team on the net.
The coach stands behind the T-line feeding the ball to one of the baseliners. Like mentioned above, they are working on their passing shots, so no lobs allowed.
The volleyers cover the court together as good as they can, so if the feed of the coach, or their volleys (once in the rally) goes to the left, both players move to the left, trying to keep the same distance between eachother.
In the video you notice that one of the players (the one standing cross-court from the baseliner hitting the ball) is always a little bit further behind, this is to make sure the lobbing is not to easy (ok… no lobs allowed in this drill, but let’s keep the good habits J).
As you can see, there is a red zone, in this drill the volleyers are not allowed to play drop shots or short volleys, they are working on their deep volleys.