Minisode which looks as though it's going to fill-in what happened when the Doctor and River met Mr Fish (referred back to in the earlier episode The Impossible Astronaut), but then sadly doesn't. A missed opportunity. They had a fish right there in the TARDIS and everything.
Anyway, I think I'd plonk this straight after Space/Time, because in that Amy said that she wanted to ask the Doctor a question, which she then didn't, and here she seems to be making another attempt. It's also kind of funny how the Doctor and Rory seem to be quietly bonding without her.
It is difficult to see what the motivation is for this DVD-only piece of slapstick. The previous series' specially-shot extra scenes had the agenda of filling in gaps between episodes. This one makes no claim as to when it happens, ties no loose threads up, and thanks to implied off-camera events - both before and after the action - feels more like it comes between two other minisodes that I've missed.
Would it be too much to hope to see those released with the following series?