[BerntR]

What is meant by a connected (compact?) swing? How is it done? How is the connection broken?

I guess this has something to do with rhythm, Air.

The connection is broken when the rhythm is broken. Hips leads shoulders. Shoulders leads hands. Hands leads clubhead. All lagging components searches their inline condition. The club is inline when it has caught up with the hands etc. This is however just a brief spot on an overtaking process when the lagging component takes the lead and the swing decelerates. And when that happens you are disconnected.