Swarm lost...and found!

To recap: in the past couple of days, one of the hives cast a small swarm (perhaps as a supersedure).  I captured it in a nuc box and it soon thereafter left for the apple tree.

Then, yesterday morning, the cluster was gone and we all wished them good luck.
This morning, when out in the yard, I saw unusual activity around #3 hive stand.  I was trying to see what was going on when I noticed something even more unusual on the opposite side of the bridge.

 

What was going on?  I looked closely and saw a number of scouts dancing.

If you look at the video closely, you will see something special.  Here is a hint:

Here is the answer:

This cluster is just too small to survive.  There are not enough bees to take care of any brood let alone build comb for the queen to lay eggs in.  They seem to be deciding on a new home and will soon leave.