This was an important day. This was the day that the owlets were bouncing off the walls so much that DH moved out of the nest in the middle of the day. It was that bad.
In this video, you can see how crowded the nest box is getting, and how rambunctious the ruckus. (The noises you hear outside are those of a graduation ceremony at the park a block away.)
Here, it looks to me like this is #5 working his wings a bit:
And the final flapping session that drove DH out (she left 5 minutes later):
DH did return to the nest box that evening, and made the particular kinds of noises she always makes when she's been away from the owlets for longer than average (as in, an entire hour instead of just a few minutes.) In this case, she was gone for over 5 hours:
The other milestone was that an owlet successfully made it up into the hole and sat there momentarily before (apparently, to my anthropomorphizing eye) seeing something frightful out in the world, and jumping back into the nest to hurriedly bury its head under a sibling. We have a healthy bat population so there are 6 or 8 of them whizzing right past the nest box every evening. My guess is that a bat is what scared the owlet.